小编h02*_*001的帖子

如何.^在MATLAB中重新定义指数函数？从:

x.^y

至:

sign(x).*abs(x.^y))

m = 10; c = 2; k = 5; F = 12;

NDSolve[{m*x''[t] + c*x'[t] + (k*Sin[2*Pi*f*t])*x[t] == F*Sin[2*Pi*f*t], 
         x[0] == 0, x'[0] == 0}, x[t], {t, 0, 30}] 

{f,0,5}}(0 = <f <= 5)

如何绘制三维图像:

x = u(t,f)

............

如果f = 0.1,0.2,... 5,我们可以求解等式:

NDSolve[{m*x''[t] + c*x'[t] + (k*Sin[2*Pi*f*t])*x[t] == F*Sin[2*Pi*f*t], 
         x[0] == 0, x'[0] == 0}, x[t], {t, 0, 30}] 

x是t和f的函数

...............

m = 10; c = 2; k = 5; F = 12;

f = 0.1

s = NDSolve[{m*x''[t] …