integration of a vector

3*cos(phi)*(9*cos(phi)*cos(theta)^2*sin(phi) + 9*cos(phi)*sin(phi)*sin(theta)^2) + 9*cos(3*cos(theta)*sin(phi))*sin(phi)^2*sin(theta) + 9*sin(3*cos(theta)*sin(phi))*cos(theta)*sin(phi)^2

this my integrand.

I want to integrate it with this.

int(integrand,phi,phi0,phi1)

but I get sigma sign in the answer of this integral even though I do not use sigma sign.

Why is that happening ?

[Jan]

Please post the code you use.

Answer 1

[Paul]

I'm not sure what "sigma sign" is, but running here, without any manipulation of integrand, does not yield a result that contains a "sigma sign." The live script display does simplify the display of the result by showing it in terms of sigma_1, but that's an expression: sigma_1 = 3*cos(theta)*sin(phi)

syms phi theta phi0 phi1
integrand = 3*cos(phi)*(9*cos(phi)*cos(theta)^2*sin(phi) + 9*cos(phi)*sin(phi)*sin(theta)^2) + 9*cos(3*cos(theta)*sin(phi))*sin(phi)^2*sin(theta) + 9*sin(3*cos(theta)*sin(phi))*cos(theta)*sin(phi)^2

integrand = 

int(integrand,phi,phi0,phi1)

ans =