Hi

This is the problem:

deq := (2*.1)*[(y(t)*(diff(y(t), t, t))-1)*(1+(diff(y(t), t))^2)^(3/2)-y(t)*(diff(y(t), t))^2*(diff(y(t), t, t))*sqrt(1+(diff(y(t), t))^2)]-2*sin(t)*(1+(diff(y(t), t))^2)^2 = 0;

dsolve({deq, y(0) = 0, (D(y))(0) = 0}, y(t), numeric)

Error, (in DEtools/convertsys) unable to convert to an explicit first-order system

So Maple signs an error, but I don't know why.

Any help will be appreciated.

Hello,

I have this differential equation:

deq := (diff(y(x), x, x))*y(x)-1+x*y(x)^2 = cos(x);

sol := dsolve({deq, y(0) = 1, (D(y))(0) = 1}, numeric);

After that I have a numerical solution for y, and for diff(y(x),x). But I would like to plot diff(y(x),x,x). (and then diff(y(x),x,x)+diff(y(x),x)*cos(x)). How can I do that?

Any help will be appreciated,

L

Hello

I have the following nonlinear differential equation:

deq := (diff(y(x), x, x))*y(x)-1+x*y(x)^2 = cos(x);

I solved it numerically:

sol := dsolve({deq, y(0) = 1, (D(y))(0) = 1}, numeric);

ysol := proc (x) options operator, arrow; rhs(sol(x)[2]) end proc;

plot('ysol(x)', x = 0 .. 5);

but I would like to substitute it to the left side of deq and plot it, to be sure that it's plot is the same as cos(x).