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Cimpriča. \end_layout \begin_layout Part Teorija \end_layout \begin_layout Section Prvi semester \end_layout \begin_layout Subsection Vektorji v \begin_inset Formula $\mathbb{R}^{n}$ \end_inset \end_layout \begin_layout Standard Identificaramo \begin_inset Formula $n-$ \end_inset terice realnih števil, točke v \begin_inset Formula $\mathbb{R}^{n}$ \end_inset , množice paroma enakih geometrijskih vektorjev. \end_layout \begin_layout Standard Osnovne operacije z vektorji: Vsota (po komponentah) in množenje s skalarjem (po komponentah), kjer je skalar realno število. \end_layout \begin_layout Standard Lastnosti teh računskih operacij: asociativnost in komutativnost vsote, aditivna enota, \begin_inset Formula $-\vec{a}=\left(-1\right)\cdot\vec{a}$ \end_inset , leva in desna distributivnost, homogenost, multiplikativna enota. \end_layout \begin_layout Subsubsection Linearna kombinacija vektorjev \end_layout \begin_layout Definition* Linearna kombinacija vektorjev \begin_inset Formula $\vec{v_{1}},\dots,\vec{v_{n}}$ \end_inset je izraz oblike \begin_inset Formula $\alpha_{1}\vec{v_{1}}+\cdots+\alpha_{n}\vec{v_{n}}$ \end_inset , kjer so \begin_inset Formula $\alpha_{1},\dots,\alpha_{n}$ \end_inset skalarji. \end_layout \begin_layout Standard \begin_inset Separator plain \end_inset \end_layout \begin_layout Definition* Množico vseh linearnih kombinacij vektorjev \begin_inset Formula $\vec{v_{1}},\dots,\vec{v_{n}}$ \end_inset označimo z \begin_inset Formula $\Lin\left\{ \vec{v_{1}},\dots,\vec{v_{n}}\right\} $ \end_inset in ji pravimo linearna ogrinjača (angl. span). \begin_inset Formula $\Lin\left\{ \vec{v_{1}},\dots,\vec{v_{n}}\right\} =\left\{ \alpha_{1}\vec{v_{1}}+\cdots+\alpha_{n}\vec{v_{n}};\forall\alpha_{1},\dots,\alpha_{n}\in\mathbb{R}\right\} $ \end_inset \end_layout \begin_layout Subsubsection Linearna neodvisnost vektorjev \end_layout \begin_layout Paragraph* Ideja \end_layout \begin_layout Standard En vektor je linearno neodvisen, če ni enak \begin_inset Formula $\vec{0}$ \end_inset . Dva, če ne ležita na isti premici. Trije, če ne ležijo na isti ravnini. \end_layout \begin_layout Definition \begin_inset CommandInset label LatexCommand label name "def:odvisni" \end_inset Vektorji \begin_inset Formula $\vec{v_{1}},\dots,\vec{v_{n}}$ \end_inset so linearno odvisni, če se da enega izmed njih izraziti z linearno kombinacijo preostalih \begin_inset Formula $n-1$ \end_inset vektorjev. Vektorji so linearno neodvisni, če niso linearno odvisni (in obratno). \end_layout \begin_layout Standard \begin_inset Separator plain \end_inset \end_layout \begin_layout Definition \begin_inset CommandInset label LatexCommand label name "def:vsi0" \end_inset Vektorji \begin_inset Formula $v_{1},\dots,v_{n}$ \end_inset so linearno neodvisni, če za vsake skalarje, ki zadoščajo \begin_inset Formula $\alpha_{1}v_{1}+\cdots+\alpha_{n}v_{n}=0$ \end_inset , velja \begin_inset Formula $\alpha_{1}=\cdots=\alpha_{n}=0$ \end_inset . ZDB poleg \begin_inset Formula $\alpha_{1}=\cdots=\alpha_{n}=0$ \end_inset ne obstajajo nobeni drugi \begin_inset Formula $\alpha_{1},\dots,\alpha_{n}$ \end_inset , kjer bi veljalo \begin_inset Formula $\alpha_{1}v_{1}+\cdots+\alpha_{n}v_{n}=0$ \end_inset . \end_layout \begin_layout Standard \begin_inset Separator plain \end_inset \end_layout \begin_layout Definition \begin_inset CommandInset label LatexCommand label name "def:kvečjemu1" \end_inset \begin_inset Formula $v_{1},\dots,v_{n}$ \end_inset so linearno neodvisni, če se da vsak vektor na kvečjemu en način izraziti kot linearno kombinacijo \begin_inset Formula $v_{1},\dots,v_{n}$ \end_inset . \end_layout \begin_layout Theorem* Te tri definicije so ekvivalentne. \end_layout \begin_layout Proof Dokazujemo ekvivalenco: \end_layout \begin_deeper \begin_layout Labeling \labelwidthstring 00.00.0000 \begin_inset Formula $\left(\ref{def:odvisni}\Rightarrow\ref{def:vsi0}\right)$ \end_inset Recimo, da so \begin_inset Formula $v_{1},\dots,v_{n}$ \end_inset linearno odvisni v smislu \begin_inset CommandInset ref LatexCommand ref reference "def:odvisni" plural "false" caps "false" noprefix "false" nolink "false" \end_inset . Dokažimo, da so tedaj linearno odvisni tudi v smislu \begin_inset Formula $\ref{def:vsi0}$ \end_inset . Obstaja tak \begin_inset Formula $i$ \end_inset , da lahko \begin_inset Formula $v_{i}$ \end_inset izrazimo z linearno kombinacijo preostalih, torej \begin_inset Formula $v_{i}=\alpha_{1}v_{1}+\cdots+\alpha_{i-1}v_{i-1}+\alpha_{i+1}v_{i+1}+\cdots+\alpha_{n}v_{n}$ \end_inset za neke \begin_inset Formula $\alpha$ \end_inset . Sledi \begin_inset Formula $0=\alpha_{1}v_{1}+\cdots+\alpha_{i-1}v_{i-1}+\left(-1\right)v_{i}+\alpha_{i+1}v_{i+1}+\cdots+\alpha_{n}v_{n}$ \end_inset , kar pomeni, da obstaja linearna kombinacija, ki je enaka 0, toda niso vsi koeficienti 0 (že koeficient pred \begin_inset Formula $v_{i}$ \end_inset je \begin_inset Formula $-1$ \end_inset ), tedaj so vektorji po definiciji \begin_inset CommandInset ref LatexCommand ref reference "def:vsi0" plural "false" caps "false" noprefix "false" nolink "false" \end_inset linearno odvisni. \end_layout \begin_layout Labeling \labelwidthstring 00.00.0000 \begin_inset Formula $\left(\ref{def:vsi0}\Rightarrow\ref{def:odvisni}\right)$ \end_inset Recimo, da so \begin_inset Formula $v_{1},\dots,v_{n}$ \end_inset linearno odvisno v smislu \begin_inset Formula $\ref{def:vsi0}$ \end_inset . Tedaj obstajajo \begin_inset Formula $\alpha$ \end_inset , ki niso vse 0, da velja \begin_inset Formula $\alpha_{1}v_{1}+\cdots+\alpha_{n}v_{n}=0$ \end_inset . Tedaj \begin_inset Formula $\exists i\ni:\alpha_{i}\not=0$ \end_inset in velja \begin_inset Formula \[ \alpha_{i}v_{i}=-\alpha_{1}v_{1}-\cdots-\alpha_{i-1}v_{i-1}-\alpha_{i+1}v_{i+1}-\cdots-\alpha_{n}v_{n}\quad\quad\quad\quad/:\alpha_{i} \] \end_inset \begin_inset Formula \[ v_{i}=-\frac{\alpha_{1}}{\alpha_{i}}v_{i}-\cdots-\frac{\alpha_{i-1}}{\alpha_{i}}v_{i-1}-\frac{\alpha_{i+1}}{\alpha_{i}}v_{i+1}-\cdots-\frac{\alpha_{n}}{\alpha_{i}}v_{n}\text{,} \] \end_inset s čimer smo \begin_inset Formula $v_{i}$ \end_inset izrazili kot linearno kombinacijo preostalih vektorjev. \end_layout \begin_layout Labeling \labelwidthstring 00.00.0000 \begin_inset Formula $\left(\ref{def:vsi0}\Leftrightarrow\ref{def:kvečjemu1}\right)$ \end_inset Naj bodo \begin_inset Formula $v_{1},\dots,v_{n}$ \end_inset LN. Recimo, da obstaja \begin_inset Formula $v$ \end_inset , ki se ga da na dva načina izraziti kot linearno kombinacijo \begin_inset Formula $v_{1},\dots,v_{n}$ \end_inset . Naj bo \begin_inset Formula $v=\alpha_{1}v_{1}+\cdots+\alpha_{n}v_{n}=\beta_{1}v_{1}+\cdots+\beta_{n}v_{n}$ \end_inset . Sledi \begin_inset Formula $0=\left(\alpha_{1}-\beta_{1}\right)v_{1}+\cdots+\left(\alpha_{n}-\beta_{n}\right)v_{n}$ \end_inset . Po definiciji \begin_inset CommandInset ref LatexCommand ref reference "def:vsi0" plural "false" caps "false" noprefix "false" nolink "false" \end_inset velja \begin_inset Formula $\forall i:\alpha_{i}-\beta_{i}=0\Leftrightarrow\alpha_{i}=\beta_{i}$ \end_inset , torej sta načina, s katerima izrazimo \begin_inset Formula $v$ \end_inset , enaka, torej lahko \begin_inset Formula $v$ \end_inset izrazimo na kvečjemu en način z \begin_inset Formula $v_{1},\dots,v_{n}$ \end_inset , kar ustreza definiciji \begin_inset CommandInset ref LatexCommand ref reference "def:kvečjemu1" plural "false" caps "false" noprefix "false" nolink "false" \end_inset . \end_layout \end_deeper \begin_layout Subsubsection Ogrodje in baza \end_layout \begin_layout Definition* Vektorji \begin_inset Formula $v_{1},\dots,v_{n}$ \end_inset so ogrodje (angl. span), če \begin_inset Formula $\Lin\left\{ v_{1},\dots,v_{n}\right\} =\mathbb{R}^{n}\Leftrightarrow\forall v\in\mathbb{R}^{n}\exists\alpha_{1},\dots,\alpha_{n}\in\mathbb{R}\ni:v=\alpha_{1}v_{1}+\cdots+\alpha_{n}v_{n}$ \end_inset . \end_layout \begin_layout Standard \begin_inset Separator plain \end_inset \end_layout \begin_layout Definition* Vektorji \begin_inset Formula $v_{1},\dots,v_{n}$ \end_inset so baza, če so LN in ogrodje \begin_inset Formula $\Leftrightarrow\forall v\in\mathbb{R}^{n}:\exists!\alpha_{1},\dots,\alpha_{n}\in\mathbb{R}\ni:v=\alpha_{1}v_{1}+\cdots+\alpha_{n}v_{n}$ \end_inset ZDB vsak vektor \begin_inset Formula $\in\mathbb{R}^{n}$ \end_inset se da na natanko en način izraziti kot LK \begin_inset Formula $v_{1},\dots,v_{n}$ \end_inset . \end_layout \begin_layout Example* Primer baze je standardna baza \begin_inset Formula $\mathbb{R}^{n}$ \end_inset : \begin_inset Formula $\left\{ \left(1,0,0,\dots,0\right),\left(0,1,0,\dots,0\right),\left(0,0,1,\dots,0\right),\left(0,0,0,\dots,1\right)\right\} $ \end_inset . To pa ni edina baza. Primer nestandardne baze v \begin_inset Formula $\mathbb{R}^{3}$ \end_inset je \begin_inset Formula $\left\{ \left(1,1,1\right),\left(0,1,1\right),\left(0,0,1\right)\right\} $ \end_inset . \end_layout \begin_layout Subsubsection Norma in skalarni produkt \end_layout \begin_layout Definition* Norma vektorja \begin_inset Formula $v=\left(\alpha_{1},\dots,\alpha_{n}\right)$ \end_inset je definirana z \begin_inset Formula $\left|\left|v\right|\right|=\sqrt{\alpha_{1}^{2}+\cdots+\alpha_{n}^{2}}$ \end_inset . Geometrijski pomen norme je dolžina krajevnega vektorja z glavo v \begin_inset Formula $v$ \end_inset . \end_layout \begin_layout Standard Osnovne lastnosti norme: \begin_inset Formula $\left|\left|v\right|\right|\geq0$ \end_inset , \begin_inset Formula $\left|\left|v\right|\right|=0\Rightarrow v=\vec{0}$ \end_inset , \begin_inset Formula $\left|\left|\alpha v\right|\right|=\left|\alpha\right|\cdot\left|\left|v\right|\right|$ \end_inset , \begin_inset Formula $\left|\left|u+v\right|\right|\leq\left|\left|u\right|\right|+\left|\left|v\right|\right|$ \end_inset (trikotniška neenakost) \end_layout \begin_layout Definition* Skalarni produkt \begin_inset Formula $u=\left(\alpha_{1},\dots,\alpha_{n}\right),v=\left(\beta_{1},\dots,\beta_{n}\right)$ \end_inset označimo z \begin_inset Formula $\left\langle u,v\right\rangle \coloneqq\alpha_{1}\beta_{1}+\cdots+\alpha_{n}\beta_{n}$ \end_inset . Obstaja tudi druga oznaka in pripadajoča drugačna definicija \begin_inset Formula $u\cdot v\coloneqq\left|\left|u\right|\right|\cdot\left|\left|v\right|\right|\cdot\cos\varphi$ \end_inset , kjer je \begin_inset Formula $\varphi$ \end_inset kot med \begin_inset Formula $u,v$ \end_inset . \end_layout \begin_layout Claim* Velja \begin_inset Formula $\left\langle u,v\right\rangle =u\cdot v$ \end_inset . \end_layout \begin_layout Proof Uporabimo kosinusni izrek, ki pravi, da v trikotniku s stranicami dolžin \begin_inset Formula $a,b,c$ \end_inset velja \begin_inset Formula $c^{2}=a^{2}+b^{2}-2ab\cos\varphi$ \end_inset , kjer je \begin_inset Formula $\varphi$ \end_inset kot med \begin_inset Formula $b$ \end_inset in \begin_inset Formula $c$ \end_inset . Za vektorja \begin_inset Formula $v$ \end_inset in \begin_inset Formula $u$ \end_inset z vmesnim kotom \begin_inset Formula $\varphi$ \end_inset torej velja \begin_inset Formula \[ \left|\left|u-v\right|\right|^{2}=\left|\left|u\right|\right|^{2}+\left|\left|v\right|\right|^{2}-2\left|\left|u\right|\right|\cdot\left|\left|v\right|\right|\cdot\cos\varphi. \] \end_inset Obenem velja \begin_inset Formula $\left|\left|u\right|\right|^{2}=\alpha_{1}^{2}+\cdots+\alpha_{n}^{2}=\left\langle u,u\right\rangle $ \end_inset , torej lahko zgornjo enačbo prepišemo v \begin_inset Formula \[ \left\langle u-v,u-v\right\rangle =\left\langle u,u\right\rangle +\left\langle v,v\right\rangle -2\left|\left|u\right|\right|\cdot\left|\left|v\right|\right|\cdot\cos\varphi. \] \end_inset Naj bo \begin_inset Formula $w=u,v$ \end_inset . Iz prihodnosti si izposodimo obe linearnosti in simetričnost. \begin_inset Formula \[ \left\langle u-v,u-v\right\rangle =\left\langle u-v,w\right\rangle =\left\langle u,w\right\rangle -\left\langle v,w\right\rangle =\left\langle u,u-v\right\rangle -\left\langle v,u-v\right\rangle =\left\langle u,u\right\rangle -\left\langle u,v\right\rangle -\left\langle v,u\right\rangle +\left\langle v,v\right\rangle \] \end_inset Prišli smo do enačbe \begin_inset Formula \[ \cancel{\left\langle u,u\right\rangle }-2\left\langle u,v\right\rangle +\cancel{\left\langle v,v\right\rangle }=\cancel{\left\langle u,u\right\rangle }+\cancel{\left\langle v,v\right\rangle }-2\left|\left|u\right|\right|\cdot\left|\left|v\right|\right|\cdot\cos\varphi\quad\quad\quad\quad/:-2 \] \end_inset \begin_inset Formula \[ \left\langle u,v\right\rangle =\left|\left|u\right|\right|\cdot\left|\left|v\right|\right|\cdot\cos\varphi. \] \end_inset \end_layout \begin_layout Claim* Paralelogramska identiteta. \begin_inset Formula $\left|\left|u+v\right|\right|^{2}+\left|\left|u-v\right|\right|^{2}=2\left|\left|u\right|\right|^{2}+2\left|\left|v\right|\right|^{2}$ \end_inset ZDB vsota kvadratov dolžin obeh diagonal je enota vsoti kvadratov dolžin vseh štirih stranic. \end_layout \begin_layout Proof \begin_inset Formula \[ \left|\left|u+v\right|\right|^{2}=\left\langle u+v,u+v\right\rangle =\left\langle u,u+v\right\rangle +\left\langle v,u+v\right\rangle =\left\langle u,u\right\rangle +\left\langle u,v\right\rangle +\left\langle v,u\right\rangle +\left\langle v,v\right\rangle \] \end_inset \begin_inset Formula \[ \left|\left|u-v\right|\right|^{2}=\left\langle u-v,u-v\right\rangle =\left\langle u,u-v\right\rangle -\left\langle v,u-v\right\rangle =\left\langle u,u\right\rangle -\left\langle u,v\right\rangle -\left\langle v,u\right\rangle +\left\langle v,v\right\rangle \] \end_inset \begin_inset Formula \[ \left|\left|u+v\right|\right|^{2}+\left|\left|u-v\right|\right|^{2}=2\left\langle u,u\right\rangle +2\left\langle v,v\right\rangle =2\left|\left|u\right|\right|^{2}+2\left|\left|v\right|\right|^{2} \] \end_inset \end_layout \begin_layout Claim* Cauchy-Schwarzova neenakost. \begin_inset Formula $\left|\left\langle u,v\right\rangle \right|\leq\left|\left|u\right|\right|\cdot\left|\left|v\right|\right|$ \end_inset \end_layout \begin_layout Proof \begin_inset Formula $\left|\left\langle u,v\right\rangle \right|=\left|\left|\left|u\right|\right|\cdot\left|\left|v\right|\right|\cdot\cos\varphi\right|=\left|\left|u\right|\right|\cdot\left|\left|v\right|\right|\cdot\left|\cos\varphi\right|\leq\left|\left|u\right|\right|\cdot\left|\left|v\right|\right|$ \end_inset , kajti \begin_inset Formula $\left|\cos\varphi\right|\in\left[0,1\right]$ \end_inset . \end_layout \begin_layout Claim* Trikotniška neenakost. \begin_inset Formula $\left|\left|u+v\right|\right|\leq\left|\left|u\right|\right|+\left|\left|v\right|\right|$ \end_inset \end_layout \begin_layout Proof Sledi iz Cauchy-Schwarzove. Velja \begin_inset Formula \[ -\left|\left|u\right|\right|\cdot\left|\left|v\right|\right|\leq\left|\left\langle u,v\right\rangle \right|\leq\left|\left|u\right|\right|\cdot\left|\left|v\right|\right|\quad\quad\quad\quad/\cdot2 \] \end_inset \begin_inset Formula \[ -2\left|\left|u\right|\right|\cdot\left|\left|v\right|\right|\leq2\left|\left\langle u,v\right\rangle \right|\leq2\left|\left|u\right|\right|\cdot\left|\left|v\right|\right|\quad\quad\quad\quad/+\left|\left|u\right|\right|^{2}+\left|\left|v\right|\right|^{2} \] \end_inset \begin_inset Formula \[ -2\left|\left|u\right|\right|\cdot\left|\left|v\right|\right|+\left|\left|u\right|\right|^{2}+\left|\left|v\right|\right|^{2}\leq\cancel{2\left|\left\langle u,v\right\rangle \right|+\left|\left|u\right|\right|^{2}+\left|\left|v\right|\right|^{2}\leq}2\left|\left|u\right|\right|\cdot\left|\left|v\right|\right|+\left|\left|u\right|\right|^{2}+\left|\left|v\right|\right|^{2} \] \end_inset uporabimo kosinusni izrek na levi strani enačbe, desno pa zložimo v kvadrat: \begin_inset Formula \[ \left|\left|u+v\right|\right|^{2}\leq\left(\left|\left|u\right|\right|+\left|\left|v\right|\right|\right)^{2}\quad\quad\quad\quad/\sqrt{} \] \end_inset \begin_inset Formula \[ \left|\left|u+v\right|\right|\leq\left|\left|u\right|\right|+\left|\left|v\right|\right| \] \end_inset \end_layout \begin_layout Claim* Za neničelna vektorja velja \begin_inset Formula $u\perp v\Leftrightarrow\left\langle u,v\right\rangle =0$ \end_inset . \end_layout \begin_layout Proof \begin_inset Formula $\left\langle u,v\right\rangle =u\cdot v=\left|\left|u\right|\right|\cdot\left|\left|v\right|\right|\cdot\cos\varphi$ \end_inset , kar je 0 \begin_inset Formula $\Leftrightarrow\varphi=\pi=90°$ \end_inset . \end_layout \begin_layout Subsubsection Vektorski in mešani produkt \end_layout \begin_layout Standard Definirana sta le za vektorje v \begin_inset Formula $\mathbb{R}^{3}$ \end_inset . \end_layout \begin_layout Definition* Naj bo \begin_inset Formula $u=\left(\alpha_{1},\alpha_{2},\alpha_{3}\right),v=\left(\beta_{1},\beta_{2},\beta_{3}\right)$ \end_inset . \begin_inset Formula $u\times v=\left(\alpha_{2}\beta_{3}-\alpha_{3}\beta_{2},\alpha_{3}\beta_{1}-\alpha_{1}\beta_{3},\alpha_{1}\beta_{2}-\alpha_{2}\beta_{1}\right)$ \end_inset . \end_layout \begin_layout Paragraph Geometrijski pomen \end_layout \begin_layout Standard Vektor \begin_inset Formula $u\times v$ \end_inset je pravokoten na \begin_inset Formula $u$ \end_inset in \begin_inset Formula $v$ \end_inset , njegova dolžina je \begin_inset Formula $\left|\left|u\right|\right|\cdot\left|\left|v\right|\right|\cdot\sin\varphi$ \end_inset , kar je ploščina paralelograma, ki ga oklepata \begin_inset Formula $u$ \end_inset in \begin_inset Formula $v$ \end_inset . \end_layout \begin_layout Standard Pravilo desnega vijaka nam je v pomoč pri doložanju usmeritve vektorskega produkta. Če iztegnjen kazalec desne roke predstavlja \begin_inset Formula $u$ \end_inset in iztegnjen sredinec \begin_inset Formula $v$ \end_inset , iztegnjen palec kaže v smeri \begin_inset Formula $u\times v$ \end_inset . \end_layout \begin_layout Claim* Lagrangeva identiteta. \begin_inset Formula $\left|\left|u\times v\right|\right|+\left\langle u,v\right\rangle ^{2}=\left|\left|u\right|\right|^{2}\cdot\left|\left|v\right|\right|^{2}$ \end_inset \begin_inset Note Note status open \begin_layout Plain Layout DOKAZ??????? \end_layout \end_inset \end_layout \begin_layout Definition* Mešani produkt vektorjev \begin_inset Formula $u,v,w$ \end_inset je skalar \begin_inset Formula $\left\langle u\times v,w\right\rangle $ \end_inset . Oznaka: \begin_inset Formula $\left[u,v,w\right]=\left\langle u\times v,w\right\rangle $ \end_inset . \end_layout \begin_layout Paragraph* Geometrijski pomen \end_layout \begin_layout Standard Volumen paralelpipeda, ki ga določajo \begin_inset Formula $u,v,w$ \end_inset . Razlaga: \begin_inset Formula $\left[u,v,w\right]=\left\langle u\times v,w\right\rangle =\left|\left|u\times v\right|\right|\cdot\left|\left|w\right|\right|\cdot\cos\varphi$ \end_inset ; \begin_inset Formula $\left|\left|u\times v\right|\right|$ \end_inset je namreč ploščina osnovne ploskve, \begin_inset Formula $\left|\left|w\right|\right|\cdot\cos\varphi$ \end_inset pa je višina paralelpipeda. \end_layout \begin_layout Claim* Osnovne lastnosti vektorskega produkta so \begin_inset Formula $u\times u=0$ \end_inset , \begin_inset Formula $u\times v=-\left(v\times u\right)$ \end_inset , \begin_inset Formula $\left(\alpha u+\beta v\right)\times w=\alpha\left(u\times w\right)+\beta\left(v\times w\right)$ \end_inset (linearnost) \end_layout \begin_layout Standard \begin_inset Separator plain \end_inset \end_layout \begin_layout Claim* Osnovne lastnosti mešanega produkta so linearnost v vsakem faktorju, menjava dveh faktorjev spremeni predznak ( \begin_inset Formula $\left[u,v,w\right]=-\left[v,u,w\right]$ \end_inset ), cikličen pomik ne spremeni vrednosti ( \begin_inset Formula $\left[u,v,w\right]=\left[v,w,u\right]=\left[w,u,v\right]$ \end_inset ). \end_layout \begin_layout Subsubsection Premica v \begin_inset Formula $\mathbb{R}^{n}$ \end_inset \end_layout \begin_layout Standard Premico lahko podamo z \end_layout \begin_layout Itemize dvema različnima točkama \end_layout \begin_layout Itemize s točko \begin_inset Formula $\vec{r_{0}}$ \end_inset in neničelnim smernim vektorjem \begin_inset Formula $\vec{p}$ \end_inset . Premica je tako množica točk \begin_inset Formula $\left\{ \vec{r}=\vec{r_{0}}+t\vec{p};\forall t\in\mathbb{R}\right\} $ \end_inset . Taki enačbi premice rečemo parametrična. \end_layout \begin_layout Itemize s točko in normalo (v \begin_inset Formula $\mathbb{R}^{2}$ \end_inset ; v \begin_inset Formula $\mathbb{R}^{n}$ \end_inset potrebujemo točko in \begin_inset Formula $n-1$ \end_inset normal) \end_layout \begin_layout Standard Nadaljujmo s parametričnim zapisom \begin_inset Formula $\vec{r}=\vec{r_{0}}+t\vec{p}$ \end_inset . Če točke zapišemo po komponentah, dobimo parametrično enačbo premice po komponentah: \begin_inset Formula $\left(x,y,z\right)=\left(x_{0},y_{0},z_{0}\right)+t\left(p_{1},p_{2},p_{3}\right)$ \end_inset . \begin_inset Formula \[ x=x_{0}+tp_{1} \] \end_inset \begin_inset Formula \[ y=y_{0}+tp_{2} \] \end_inset \begin_inset Formula \[ z=z_{0}+tp_{3} \] \end_inset \end_layout \begin_layout Standard Sedaj lahko iz vsake enačbe izrazimo \begin_inset Formula $t$ \end_inset in dobimo normalno enačbo premice v \begin_inset Formula $\mathbb{R}^{n}$ \end_inset : \begin_inset Formula \[ t=\frac{x-x_{0}}{p_{1}}=\frac{y-y_{0}}{p_{2}}=\frac{z-z_{0}}{p_{3}}\text{, oziroma v splošnem za premico v \ensuremath{\mathbb{R}^{n}}: }t=\frac{x_{1_{0}}-x_{1}}{p_{1}}=\cdots=\frac{x_{n_{0}}-x_{n}}{p_{n}} \] \end_inset \end_layout \begin_layout Standard Osnovne naloge s premicami so projekcija točke na premico, zrcaljenje točke čez premico in razdalja med točko in premico. \end_layout \begin_layout Paragraph* Iskanje projekcije dane točke na dano premico \end_layout \begin_layout Standard (skica prepuščena bralcu) \begin_inset Formula $\vec{r_{1}}$ \end_inset projiciramo na \begin_inset Formula $\vec{r}=\vec{r_{0}}+t\vec{p}$ \end_inset in dobimo \begin_inset Formula $\vec{r_{1}'}$ \end_inset . Za \begin_inset Formula $\vec{r_{1}'}$ \end_inset vemo, da leži na premici, torej \begin_inset Formula $\exists t\in\mathbb{R}\ni:\vec{r_{1}'}=\vec{r_{0}}+t\vec{p}$ \end_inset . Poleg tega vemo, da je \begin_inset Formula $\vec{r_{1}'}-\vec{r_{1}}$ \end_inset pravokoten na premico oz. njen smerni vektor \begin_inset Formula $\vec{p}$ \end_inset , torej \begin_inset Formula $\left\langle \vec{r_{1}'}-\vec{r_{1}},\vec{p}\right\rangle =0$ \end_inset . Ti dve enačbi združimo, da dobimo \begin_inset Formula $t$ \end_inset , ki ga nato vstavimo v prvo enačbo: \begin_inset Formula \[ \left\langle \vec{r_{0}}+t\vec{p}-\vec{r_{1},}\vec{p}\right\rangle =0\Longrightarrow\left\langle \vec{r_{0}},\vec{p}\right\rangle +t\left\langle \vec{p},\vec{p}\right\rangle -\left\langle \vec{r_{1}},\vec{p}\right\rangle =0\Longrightarrow t=\frac{\left\langle \vec{r_{1}},\vec{p}\right\rangle -\left\langle \vec{r_{0}},\vec{p}\right\rangle }{\left\langle \vec{p},\vec{p}\right\rangle } \] \end_inset \begin_inset Formula \[ \vec{r_{1}'}=\vec{r_{0}}+t\vec{p}=\vec{r_{0}}+\frac{\left\langle \vec{r_{1}},\vec{p}\right\rangle -\left\langle \vec{r_{0}},\vec{p}\right\rangle }{\left\langle \vec{p},\vec{p}\right\rangle }\vec{p} \] \end_inset \end_layout \begin_layout Standard Spotoma si lahko izpišemo obrazec za oddaljenost točke od premice: \begin_inset Formula $a=\left|\left|\vec{r_{1}'}-\vec{r_{1}}\right|\right|$ \end_inset in obrazec za zrcalno sliko ( \begin_inset Formula $\vec{r_{1}''}$ \end_inset ): \begin_inset Formula $\vec{r_{1}'}=\frac{\vec{r_{1}''}+\vec{r_{1}}}{2}\Longrightarrow\vec{r_{1}''}=2\vec{r_{1}'}-\vec{r_{1}}$ \end_inset . \end_layout \begin_layout Subsubsection Ravnine v \begin_inset Formula $\mathbb{R}^{n}$ \end_inset \end_layout \begin_layout Standard Ravnino lahko podamo \end_layout \begin_layout Itemize s tremi nekolinearnimi točkami \end_layout \begin_layout Itemize s točko na ravnini in dvema neničelnima smernima vektorjema, ki sta linarno neodvisna. Ravnina je tako množica točk \begin_inset Formula $\left\{ \vec{r}=\vec{r_{0}}+s\vec{p}+t\vec{q};\forall s,t\in\mathbb{R}\right\} $ \end_inset . Taki enačbi ravnine rečemo parametrična. \end_layout \begin_layout Itemize s točko in na ravnini in normalo (v \begin_inset Formula $\mathbb{R}^{3}$ \end_inset ; v \begin_inset Formula $\mathbb{R}^{n}$ \end_inset poleg točke potrebujemo \begin_inset Formula $n-2$ \end_inset normal) \end_layout \begin_layout Standard Nadaljujmo s parametričnim zapisom \begin_inset Formula $\vec{r}=\vec{r_{0}}+s\vec{p}+t\vec{q}$ \end_inset . Če točke zapišemo po komponentah, dobimo parametrično enačbo ravnine po komponentah: \begin_inset Formula $\left(x,y,z\right)=\left(x_{0},y_{0},z_{0}\right)+s\left(p_{1},p_{2},p_{3}\right)+t\left(q_{1},q_{2},q_{3}\right)$ \end_inset . \end_layout \begin_layout Standard \begin_inset Formula \[ x=x_{0}+sp_{1}+tq_{1} \] \end_inset \begin_inset Formula \[ y=y_{0}+sp_{2}+tq_{2} \] \end_inset \begin_inset Formula \[ z=y_{0}+sp_{3}+tq_{3} \] \end_inset \end_layout \begin_layout Paragraph Normalna enačba ravnine v \begin_inset Formula $\mathbb{R}^{3}$ \end_inset \end_layout \begin_layout Standard (skica prepuščena bralcu) Vemo, da je \begin_inset Formula $\vec{n}$ \end_inset (normala) pravokotna na vse vektorje v ravnini, tudi na \begin_inset Formula $\vec{r}-\vec{r_{0}}$ \end_inset za poljuben \begin_inset Formula $\vec{r}$ \end_inset na ravnini. Velja torej normalna enačba ravnine: \begin_inset Formula $\left\langle \vec{r}-\vec{r_{0}},\vec{n}\right\rangle =0$ \end_inset . Razpišimo jo po komponentah, da na koncu dobimo normalno enačbo ravnine po komponentah: \begin_inset Formula \[ \left\langle \left(x,y,z\right)-\left(x_{0},y_{0},z_{0}\right),\left(n_{1},n_{2},n_{3}\right)\right\rangle =0=\left\langle \left(x-x_{0},y-y_{0},z-z_{0}\right),\left(n_{1},n_{2},n_{3}\right)\right\rangle \] \end_inset \begin_inset Formula \[ n_{1}\left(x-x_{0}\right)+n_{2}\left(y-y_{0}\right)+n_{3}\left(z-z_{0}\right)=0=n_{1}x-n_{1}x_{0}+n_{2}y-n_{2}y_{0}+n_{3}z-n_{3}z_{0}=0 \] \end_inset \begin_inset Formula \[ n_{1}x+n_{2}y+n_{3}z=n_{1}x_{0}+n_{2}y_{0}+n_{3}z_{0}=d \] \end_inset \end_layout \begin_layout Paragraph Iskanje pravokotne projekcije dane točke na dano ravnino \end_layout \begin_layout Standard (skica prepuščena bralcu) Projicirati želimo \begin_inset Formula $\vec{r_{1}}$ \end_inset v \begin_inset Formula $\vec{r_{1}'}$ \end_inset na ravnini \begin_inset Formula $\vec{r}=\vec{r_{0}}+s\vec{p}+t\vec{q}$ \end_inset . Vemo, da \begin_inset Formula $\vec{r_{1}'}$ \end_inset leži na ravnini, zato \begin_inset Formula $\exists s,t\in\mathbb{R}\ni:\vec{r_{1}'}=\vec{r_{0}}+s\vec{p}+t\vec{q}$ \end_inset . Poleg tega vemo, da je \begin_inset Formula $\vec{r_{1}'}-\vec{r_{1}}$ \end_inset pravokoten na ravnino oz. na \begin_inset Formula $\vec{p}$ \end_inset in na \begin_inset Formula $\vec{q}$ \end_inset hkrati, torej \begin_inset Formula $\left\langle \vec{r_{1}'}-\vec{r_{1}},\vec{p}\right\rangle =0=\left\langle \vec{r_{1}'}-\vec{r_{1}},\vec{q}\right\rangle $ \end_inset . Vstavimo \begin_inset Formula $\vec{r_{1}'}$ \end_inset iz prve enačbe v drugo in dobimo \begin_inset Formula \[ \left\langle \vec{r_{0}}+s\vec{p}+t\vec{q}-\vec{r_{1}},\vec{p}\right\rangle =0=\left\langle \vec{r_{0}}+s\vec{p}+t\vec{q}-\vec{r_{1}},\vec{q}\right\rangle \] \end_inset \begin_inset Formula \[ \left\langle \vec{r_{0}},\vec{p}\right\rangle +s\left\langle \vec{p},\vec{p}\right\rangle +t\left\langle \vec{q},\vec{p}\right\rangle -\left\langle \vec{r_{1}},\vec{p}\right\rangle =0=\left\langle \vec{r_{0}},\vec{q}\right\rangle +s\left\langle \vec{p},\vec{q}\right\rangle +t\left\langle \vec{q},\vec{q}\right\rangle -\left\langle \vec{r_{1}},\vec{q}\right\rangle \] \end_inset dobimo sistem dveh enačb \begin_inset Formula \[ s\left\langle \vec{p},\vec{p}\right\rangle +t\left\langle \vec{q},\vec{p}\right\rangle =\left\langle \vec{r_{1}}-\vec{r_{0}},\vec{p}\right\rangle \] \end_inset \begin_inset Formula \[ s\left\langle \vec{p},\vec{q}\right\rangle +t\left\langle \vec{q},\vec{q}\right\rangle =\left\langle \vec{r_{1}}-\vec{r_{0}},\vec{q}\right\rangle \] \end_inset sistem rešimo in dobljena \begin_inset Formula $s,t$ \end_inset vstavimo v prvo enačbo zgoraj, da dobimo \begin_inset Formula $\vec{r_{1}'}$ \end_inset . \end_layout \begin_layout Subsubsection Regresijska premica \end_layout \begin_layout Standard Regresijska premica je primer uporabe zgornje naloge. V ravnini je danih \begin_inset Formula $n$ \end_inset točk \begin_inset Formula $\left(x_{1},y_{1}\right),\dots,\left(x_{n},y_{n}\right)$ \end_inset . Iščemo tako premico \begin_inset Formula $y=ax+b$ \end_inset , ki se najbolj prilega tem točkam. Prileganje premice točkam merimo z metodo najmanjših kvadratov: naj bo \begin_inset Formula $d_{i}$ \end_inset navpična razdalja med \begin_inset Formula $\left(x_{i},y_{i}\right)$ \end_inset in premico \begin_inset Formula $y=ax+b$ \end_inset , torej razdalja med točkama \begin_inset Formula $\left(x_{i},y_{i}\right)$ \end_inset in \begin_inset Formula $\left(x_{i},ax_{i}+b\right)$ \end_inset , kar je \begin_inset Formula $\left|y_{i}-ax_{i}-b\right|$ \end_inset . Minimizirati želimo vsoto kvadratov navpičnih razdalj, torej izraz \begin_inset Formula $d_{1}^{2}+\cdots+d_{n}^{2}=\left(y_{1}-ax_{1}-b\right)^{2}+\cdots+\left(y_{n}-ax_{n}-b\right)^{2}=\left|\left|\left(y_{1}-ax_{1}-b,\dots,y_{n}-ax_{n}-b\right)\right|\right|^{2}=\left|\left|\left(y_{1},\dots,y_{n}\right)-a\left(x_{1},\dots,x_{n}\right)-b\left(1,\dots,1\right)\right|\right|^{2}$ \end_inset . \end_layout \begin_layout Standard Če je torej \begin_inset Formula $\vec{r}=\vec{0}+a\left(x_{1},\dots,x_{n}\right)+b\left(1,\dots,1\right)$ \end_inset hiperravnina v \begin_inset Formula $n-$ \end_inset dimenzionalnem prostoru, bo norma, ki jo želimo minimizirati, najmanjša tedaj, ko \begin_inset Formula $a,b$ \end_inset izberemo tako, da najdemo projekcijo \begin_inset Formula $\left(y_{1},\dots,y_{n}\right)$ \end_inset na to hiperravnino (skica prepuščena bralcu). Rešimo sedaj nalogo projekcije točke na ravnino: \end_layout \begin_layout Standard Označimo \begin_inset Formula $\vec{y}\coloneqq\left(y_{1},\dots,y_{n}\right)$ \end_inset , \begin_inset Formula $\vec{x}\coloneqq\left(x_{1},\dots,x_{n}\right)$ \end_inset \end_layout \begin_layout Section Drugi semester \end_layout \begin_layout Part Vaja za ustni izpit \end_layout \begin_layout Standard Ustni izpit je sestavljen iz treh vprašanj. Sekcije so zaporedna vprašanja na izpitu, podsekcije so učiteljevi naslovi iz Primerov vprašanj, podpodsekcije pa so dejanska vprašanja, kot so se pojavila na dosedanjih izpitih. \end_layout \begin_layout Section Prvo vprašanje \end_layout \begin_layout Standard Prvo vprašanje je iz 1. semestra. \end_layout \begin_layout Subsubsection \begin_inset Formula $\det AB=\det A\det B$ \end_inset \end_layout \begin_layout Subsection Baze vektorskega prostora \end_layout \begin_layout Subsubsection Linearno neodvisne množice \end_layout \begin_layout Subsubsection Ogrodje \end_layout \begin_layout Subsubsection Definicija baze \end_layout \begin_layout Subsubsection Dimenzija prostora \end_layout \begin_layout Subsection Cramerovo pravilo \end_layout \begin_layout Subsubsection Trditev in dokaz \end_layout \begin_layout Subsection Obrnljive matrike \end_layout \begin_layout Subsubsection Definicija obrnljivosti \end_layout \begin_layout Subsubsection Produkt obrnljivih matrik je obrnljiva matrika \end_layout \begin_layout Subsubsection Karakterizacija obrnljivih matrik z dokazom \end_layout \begin_layout Subsubsection \begin_inset Formula $\Ker A=\left\{ 0\right\} \Leftrightarrow A$ \end_inset obrnljiva \end_layout \begin_layout Subsubsection \begin_inset Formula $A$ \end_inset ima desni inverz \begin_inset Formula $\Rightarrow A$ \end_inset obrnljiva \end_layout \begin_layout Subsubsection Formula za inverz matrike z dokazom \end_layout \begin_layout Subsection Vektorski podprostori \end_layout \begin_layout Subsection Elementarne matrike \end_layout \begin_layout Subsection Pod-/predoločeni sistem \end_layout \begin_layout Subsubsection Definicija, iskanje posplošene rešitve z izpeljavo \end_layout \begin_layout Subsubsection Moč ogrodja \begin_inset Formula $\geq$ \end_inset moč LN množice \end_layout \begin_layout Subsubsection Vsak poddoločen sistem ima netrivialno rešitev \end_layout \begin_layout Standard Posledica prejšnje trditve. \end_layout \begin_layout Subsection Regresijska premica \end_layout \begin_layout Subsubsection Definicija \end_layout \begin_layout Subsection Vektorski/mešani produkt \end_layout \begin_layout Subsection Grupe/polgrupe \end_layout \begin_layout Subsubsection Definicija in lastnosti grupe \end_layout \begin_layout Subsubsection Definicija homomorfizma \end_layout \begin_layout Subsubsection Primeri homomorfizmov z dokazi \end_layout \begin_layout Subsubsection Definicija permutacijske grupe in dokaz, da je grupa \end_layout \begin_layout Subsubsection Primeri grup \end_layout \begin_layout Subsubsection Dokaz, da so ortogonalne matrike podgrupa v grupi obrnljivih matrik \end_layout \begin_layout Subsubsection Matrika permutacije \end_layout \begin_layout Subsubsection Dokaz, da je preslikava, ki permutaciji priredi matriko, homomorfizem \end_layout \begin_layout Subsection Projekcija točke na premico/ravnino \end_layout \begin_layout Subsection \begin_inset Formula $\det A=\det A^{T}$ \end_inset \end_layout \begin_layout Subsection Formula za inverz \end_layout \begin_layout Subsection Homogeni sistemi enačb \end_layout \begin_layout Section Drugo vprašanje \end_layout \begin_layout Standard Drugo vprašanje zajema snov linearnih preslikav/lastnih vrednosti. \end_layout \begin_layout Subsection Diagonalizacija \end_layout \begin_layout Subsubsection Definicija, trditve \end_layout \begin_layout Subsection Prehod na novo bazo \end_layout \begin_layout Subsubsection Prehodna matrika in njene lastnosti \end_layout \begin_layout Subsubsection Predstavitev vektorjev in linearnih preslikav z različnimi bazami \end_layout \begin_layout Subsubsection Razvoj vektorja po eni in drugi bazi (prehod vektorja na drugo bazo) \end_layout \begin_layout Subsection Matrika linearne preslikave \end_layout \begin_layout Subsection Rang matrike \end_layout \begin_layout Subsubsection Definicija \end_layout \begin_layout Subsubsection Dokaz, da je rang število LN stolpcev \end_layout \begin_layout Subsubsection Dimenzijska formula za podprostore \end_layout \begin_layout Subsection \begin_inset Formula $\rang A=\rang A^{T}$ \end_inset \end_layout \begin_layout Subsection Ekvivalentnost matrik \end_layout \begin_layout Subsubsection Definicija \end_layout \begin_layout Subsubsection Dokaz, da je relacija ekvivalenčna \end_layout \begin_layout Subsubsection Dokaz, da je vsaka matrika ekvivalentna matriki \begin_inset Formula $I_{r}$ \end_inset , t. j. bločni matriki, katere zgornji levi blok je \begin_inset Formula $I$ \end_inset dimenzije \begin_inset Formula $r$ \end_inset , drugi trije bloki pa so ničelne matrike. \end_layout \begin_layout Subsection Jedro/slika \end_layout \begin_layout Subsection Minimalni poinom \end_layout \begin_layout Subsubsection Definicija karakterističnega in minimalnega polinoma \end_layout \begin_layout Subsection Cayley-Hamiltonov izrek \end_layout \begin_layout Subsubsection Trditev in dokaz \end_layout \begin_layout Subsection Korenski razcep \end_layout \begin_layout Subsubsection Definicija korenskih podprostorov \end_layout \begin_layout Subsubsection Presek različnih korenskih podprostorov je trivialen \end_layout \begin_layout Subsubsection Vsota korenskih podprostorov je direktna (se sklicuje na zgornjo trditev) \end_layout \begin_layout Subsection Osnovna formula rang \begin_inset Formula $+$ \end_inset ničnost \end_layout \begin_layout Subsubsection Definicija \end_layout \begin_layout Subsection Funkcije matrik \end_layout \begin_layout Section Tretje vprašanje \end_layout \begin_layout Standard Tretje vprašanje zajema naslednje snovi: \end_layout \begin_layout Itemize vektorski prostori s skalarnim produktom, \end_layout \begin_layout Itemize adjungirana preslikava, \end_layout \begin_layout Itemize singularni razcep, \end_layout \begin_layout Itemize kvadratne forme. \end_layout \begin_layout Subsubsection Singularni razcep: Konstrukcija \begin_inset Formula $Q_{1},Q_{2},D$ \end_inset in dokaz \begin_inset Formula $A=Q_{1}DQ_{2}^{-1}$ \end_inset . \end_layout \begin_layout Subsection Ortogonalne/unitarne matrike \end_layout \begin_layout Subsubsection Definicija \end_layout \begin_layout Subsubsection Dokaz \begin_inset Formula $AA^{*}=I$ \end_inset \end_layout \begin_layout Subsubsection Lastne vrednosti \end_layout \begin_layout Subsubsection Prehodna matrika iz ONB v drugo ONB ima ortogonalne stolpce (dokaz) \end_layout \begin_layout Subsection Kvadratne krivulje \end_layout \begin_layout Subsection Psevdoinverz \end_layout \begin_layout Subsubsection Definicija \end_layout \begin_layout Subsection Najkrajša posplošena rešitev sistema \end_layout \begin_layout Subsubsection Definicija, trditev in dokaz \end_layout \begin_layout Subsection Simetrične matrike \end_layout \begin_layout Subsubsection Vse o simetričnih matrikah \end_layout \begin_layout Subsection Adjungirana linearna preslikava \end_layout \begin_layout Subsubsection Definicija in celotna formulacija \end_layout \begin_layout Subsubsection Rieszov izrek \end_layout \begin_layout Subsubsection Dokaz obstoja in enoličnosti kot posledica Rieszovega izreka \end_layout \begin_layout Subsubsection Formula za matriko linearne preslikave in \begin_inset Formula $\left\langle Au,v\right\rangle =v^{*}Au=\left\langle u,A^{*}v\right\rangle $ \end_inset \end_layout \begin_layout Subsubsection Lastne vrednosti adjungirane matrike \end_layout \begin_layout Subsection Klasifikacija skalarnih produktov \end_layout \begin_layout Subsection Normalne matrike \end_layout \begin_layout Subsubsection Definicija, lastnosti, izreki, dokazi \end_layout \begin_layout Subsubsection \begin_inset Formula $A$ \end_inset normalna \begin_inset Formula $\Rightarrow A$ \end_inset in \begin_inset Formula $A^{*}$ \end_inset imata isto množico lastnih vrednosti \end_layout \begin_layout Subsubsection \begin_inset Formula $\Ker\left(A-xI\right)=\Ker\left(A-\overline{x}I\right)$ \end_inset za normalno \begin_inset Formula $A$ \end_inset \end_layout \begin_layout Subsection Ortogonalni komplement \end_layout \begin_layout Subsubsection Formula za ortogonalno projekcijo \end_layout \begin_layout Subsection Izrek o reprezentaciji linearnih funkcionalov \end_layout \begin_layout Subsection Pozitivno semidefinitne matrike \end_layout \begin_layout Subsubsection Definicija, lastnosti. \end_layout \begin_layout Subsubsection Dokaz, da imajo nenegativne lastne vrednosti. \end_layout \begin_layout Subsubsection Kvadratni koren pozitivno semidefinitne matrike. \end_layout \begin_layout Subsubsection \begin_inset Formula $A\geq0\Rightarrow A$ \end_inset sebiadjungirana \end_layout \begin_layout Subsection Ortogonalne in ortonormirane baze/Gram-Schmidt \end_layout \end_body \end_document