06.08.2013 Views

Web skærmformat. - Aarhus Universitet

Web skærmformat. - Aarhus Universitet

Web skærmformat. - Aarhus Universitet

SHOW MORE
SHOW LESS

You also want an ePaper? Increase the reach of your titles

YUMPU automatically turns print PDFs into web optimized ePapers that Google loves.

IV. Differentialligninger – 2. 1. ordens ligninger 333<br />

2.17. Lineært system ☞ [LA] 15 Lineært system<br />

Definition 1<br />

Ved et lineœrt differentialligningssystem (2 ligninger) med konstante koefficienter forstås<br />

dy1<br />

dx = a11y1 + a12y2 + b1<br />

dy2<br />

dx = a21y1 + a22y2 + b2<br />

En løsning er differentiable funktioner<br />

x ↦→ y1(x),x ↦→ y2(x)<br />

som indsat opfylder lignningerne.<br />

2.18. Lineært system ☞ [LA] 15 Lineært system<br />

Definition 1 - matrixform<br />

For 2 × 2-matricen A = (aij), koefficientmatricen, og 2-søjlerne b = (bi), y(x) = (yi(x)) skrives<br />

differentialligningssystem<br />

eller dy1<br />

dx<br />

dy2 =<br />

dx<br />

En løsning skrives<br />

dy<br />

= Ay + b<br />

dx<br />

<br />

a11 a12 y1<br />

a21 a22<br />

x ↦→ y(x) =<br />

y2<br />

<br />

+<br />

<br />

y1(x)<br />

y2(x)<br />

b1<br />

b2

Hooray! Your file is uploaded and ready to be published.

Saved successfully!

Ooh no, something went wrong!