How to use linspace for a function already defined?

Hi there,

I am using triple integrals to evaluate the volume of a cylindrical shaped item. I need to graph the volume as a result of an angle, but I can't seem to use linspace first to define a set of angles and then integrate after. Instead, I set the angle as a symbolic variable and did the variable, ending up with:

V1 = -125*pi*(tan(a1) - 1)

where a1 is the angle

How do I use linspace now to find V1 for a set of a1 angles? Basically, how do I turn a1 from a symbolic variable to a set of values (ex. a1 = linspace(0, pi);)

My end goal is to plot V1 as a function of a1, with a bound on a1 from 0 to pi in my example.

Let me know if this is unclear.

Thanks

Answer 1

[Walter Roberson]

a1_vals = linspace(0, pi);
V1_vals = double( subs(V1, a1, a1_vals) );
plot(a1_vals, V1_vals)

[Richard Yang]

Exactly what i needed! I originally used feval, but this fixed all my issues! Thanks!