how to use MATLAB function? T^T


function [x, y] = rk4 (f, tspan, y0, h)
a = tspan(1); b = tspan(2); n = (b-a) / h;
x = (a+h: h : b);
k1 = h * feval(f, a, y0);
k2 = h *
feval(f, a + h / 2, y0 + k1 / 2);
k3 = h * feval(f, a + h / 2, y0 + k2 / 2);
k4 = h * feval(f, a + h, y0 + k3);
y(1) = y0 + k1/6 + k2/3 + k3/3 + k4/6;
for i= 1 : n-1
k1 = h * feval(f, x(i), y(i) );
k2 = h *
feval(f, x(i) + h/2, y(i) + k1 / 2);
k3 = h * feval(f, x(i) + h/2, y(i) + k2 / 2);
k4 = h * feval(f, x(i) + h, y(i) + k3);
y(i+1) = y(i) + k1/6 + k2/3 + k3/3 + k4/6;
end
x = [ a x ];
y = [ y0 y];
function y = f(p, q)
y = exp(p) + q;
end
rk4.m, and f.m...
Use RK 4th order numerical method, solve that function..
I type at command window
> rk4(f, [0 3], 0, 0.5)
??? Input argument "p" is undefined.
Error in ==> f at 2
y = exp(p) + q;
and,
> rk4(f(0, 0), [0 3], 0, 0.5)
??? Error using ==> feval
Argument must contain a string or function_handle.
Error in ==> rk4 at 6
k1 = h * feval(f, a, y0);
Initial value is (0,0), and original function is y'=y+e^t
how can i solve this problem? please help me!
Reply to
그리핀
Loading thread data ...
"???" schrieb im Newsbeitrag news: snipped-for-privacy@a5g2000pre.googlegroups.com...
See Example in Excel VBA Code:
formatting link
Reply to
JCH

PolyTech Forum website is not affiliated with any of the manufacturers or service providers discussed here. All logos and trade names are the property of their respective owners.