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+--- Thread: Solve System of differential equations (/thread-12076.html)
Solve System of differential equations - PepePepe - 01-03-2019 09:09 AM
How can I solve a system of differential equations in the HP Prime? Something like this:
x1'=x1+2*x2
x2'=3*x1+2*x2
x2'=3*x1+2*x2
I've tried to use desolve, but it seems it only works for one differential equation.
Thanks!
RE: Solve System of differential equations - parisse - 01-03-2019 12:44 PM
desolve(y'=[[1,2],[3,2]]*y,t,y)
RE: Solve System of differential equations - PepePepe - 01-03-2019 07:39 PM
But it seems that HP Prime it's doing something wrong if I do that. For example:
desolve(y'=[[1,0],[0,2]]*y,t,y)
gives the same solution as
desolve(y'=[[1,0],[0,2]]*y + [[3],[4]] ,t,y)
I think it is because the calculator is interpreting [[1,0],[0,2]]*y as [[y,0],[0,2y]] (it doesn't take into account that y is a vector)
How could I solve this? Am I doing something wrong?
Thanks!
RE: Solve System of differential equations - parisse - 01-05-2019 08:47 PM
Correct syntax for second member is
s:=desolve(y'=[[1,0],[0,2]]*y + [3,4] ,t,y)
The reason is that y is a line vector, not a column vector. Indeed desolve returns a list of generic solutions, even for linear ODE, because you might get several generic solutions for non linear ODE. That mean that the solution y is s[0], i.e. a line vector.