I created a regular 2D without specifying the number of points. I tried to change its style from "line" to "point", but i cannot see the symbols because there are too many points and so all i see is a thick black line. Is replotting with less points the only way, or can I interactively reduce the number of points? 

For example, i have the field x*e_x+y*e_y. Is there a command for transforming it into the same field with polar coordinates and polar unit vectors?

for example, how to define f(x,y)=sin(x+y) inside a triangle but f(x,y)=0 elsewhere? 

I have defined a function 'A' and written a procedure to evaluate it for various variables, as follows:

A := r*sin(m);

Aval := proc (r, m)

evalf(A);

end proc;

Aval(1, Pi);

The function defined by its variables is returned:  r*sin(m).

How can I get maple to return the numerical value of the function?

I need maple to perform the following:

"int((1+m^2*(alpha-theta)^2*sin(theta)^2/sin(alpha)^2/alpha^2)^(1/2),theta = 0 .. alpha)"

but maple does not integrate. I have tried assuming that the term inside the square root is positive, with no result. What else can I do?