Hello,

 I want to plot the following truncated powr series with trigonometric coefficients:

sum(-y2*y3+8*(-1)^((k-1)*(1/2))*sinh(y2*Pi*k)*sin(k*Pi*y3)/(Pi^3*k^3*cosh((1/2)*k*Pi)), k = 1 .. 10)

but I get some strange terms with a strange term "I" in it which causes strange plots. I removed and it seems ok, why does this happen and what can I do to avoid it?

Hello,

 I have a function that on two variables y1,y2. I know that the different variables, y2,y3 are orthogonal, i.e. y2*y3=0, hence I want to substitute this information into the function, but it does only work if only numbers apear in the expression.

#A minimal example with numbers as coefficients and parameters as coefficents

v(y2,y3):=y2^(2)+ y2*2*y3+y3^(2);  # numbers
u(y2,y3):=y2^(2)+ y2*h*y3+y3^(2);  # parameters

Hello,

 I am getting into the pdetools, in particular the analytical options. I saw that I can test the MAPLE solution to a pde, but I want MAPLE to test my solution,  how could I do that, MAPLE just substitutes my solution into the pde without differentiating and simplifying.

Thanks,

Daniel