alfarunner

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7 years, 216 days

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These are questions asked by alfarunner

I got a double sum as a solution to heat equation in 2d. How do I plot that för different time values? 

I can't get the right syntax for add, op

 

BVP := [4*(diff(u(x, t), t))-9*(diff(u(x, t), x, x))-5*u(x, t) = 0, u(0, t) = 0, u(6, t) = 0, u(x, 0) = sin((1/6)*Pi*x)^2];
pdsolve(BVP);
        
U := unapply(rhs(sol), [x, t]);
  
plot3d(eval(U(x, t), infinity = 20), x = 0 .. 6, t = 0 .. 4);
Warning, unable to evaluate the function to numeric values in the region; see the plotting command's help page to ensure the calling sequence is correct

 

If I have a fourier series as a function of x and t and summation goes from n=1 to eternity how can I get a new function, say F, with unapply so that F=F(x,t,n)?

So instead of plotting F from n=1 to eternity I want to plot e.g from n=1 to n=10

 

Why can't MAple give me two solutions of

-2*sqrt(-K[1]^2+1)*K[1]+4*K[1]^2-Pi-2*arctan(sqrt(-K[1]^2+1)/K[1])=0

I only get -2*10^-13. There should be one K[1]=0.983 about

 

If I have a position vector r(t) i polar coordinates and want to calculate velocity I can't get maple to differentiate the unit vectors w.r.t time. How do I do that?

 

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