Solving coupled Differential equations

JaeSung Choi

2017 10 11

0 个回答

2 次查看（30 天）

0 个投票

I tried to solve following diff. eq. using 'dsolve' but (maybe) it's impossible.

So please help me how to solve following eq.s using matlab!!!!!

syms s1 s2 s3 g1 g2 g3 p1 p2 p3 t
h = 1; b = 2; e = exp(1); v = 1;
diffqp1 = 'Dp1 = h*b*s1*(g1-p3)-(e/v)*p1'
diffqp2 = 'Dp2 = h*b*s1*(g1-p3)-(e/v)*p2'
diffqp3 = 'Dp3 = h*b*s1*(g1-p3)-(e/v)*p3'
diffqs1 = 'Ds1 = -h*b*s1*(g1-p3)-(e/v)*s1'
diffqs2 = 'Ds2 = -h*b*s1*(g1-p3)-(e/v)*s2'
diffqs3 = 'Ds3 = -h*b*s1*(g1-p3)-(e/v)*s3'

3 个评论
显示 1更早的评论隐藏 1更早的评论

Walter Roberson 2017-10-11

在 MATLAB Online 中打开

Are your g1 g2 g3 functions or constants?
What boundary conditions are there?
you never use g2 or g3 but use g1 repeatedly

Presuming that g1 is a constant and not a function, then current syntax would look like

syms s1(t) s2(t) s3(t) g1 g2 g3 p1(t) p2(t) p3(t)
h = 1; b = 2; e = exp(1); v = 1;
Dp1 = diff(p1); Dp2 = diff(p2); Dp3 = diff(p3);
Ds1 = diff(s1); Ds2 = diff(s2); Ds3 = diff(s3);
diffqp1 = Dp1 == h*b*s1*(g1-p3)-(e/v)*p1;
diffqp2 = Dp2 == h*b*s1*(g1-p3)-(e/v)*p2;
diffqp3 = Dp3 == h*b*s1*(g1-p3)-(e/v)*p3;
diffqs1 = Ds1 == -h*b*s1*(g1-p3)-(e/v)*s1;
diffqs2 = Ds2 == -h*b*s1*(g1-p3)-(e/v)*s2;
diffqs3 = Ds3 == -h*b*s1*(g1-p3)-(e/v)*s3;
eqns = [diffqp1, diffqp2, diffqp3, diffqs1, diffqs2, diffqs3];
sol = dsolve(eqns);