I want to take modulus of complex number in polar coordinates in matlab .

For examle how to calculate mod of 1+ a cos(theta)+ i asin(theta) on matlab

Answer 1

[Bjorn Gustavsson]

The only definition of modulus of a complex number I can find is what is done with the abs-function. In that case you simlpy do:

z = 1+a*cos(theta) + 1i*a*sin(theta); % using 1i to make sure it is the imaginary unit. 
abs(z)

Here I also assumed that you wanted a*sin(theta) and not 1i*asin(theta)

HTH

[bushra kanwal]

but it gives only the symbol of modulus. this syntax does not provide calculated modulus

[Bjorn Gustavsson]

No it doesn't:

a = 12;
theta = sqrt(2);
z = 1+a*cos(theta) + 1i*a*sin(theta); % using 1i to make sure it is the imaginary unit. 
abs(z)
ans =

   12.1960

As it should. If you're working with symbolic variables then that's another case which you might not get further, but why bother about that, you know what it should be and can simply replace (see help and documentation for subs) it when necessary.