How to get the modulus of complex symbolic expression?

Dear all,

I want to calculate the modulus of complex symbolic expression but I do not get explicit results:

syms a b;
assume(a>0);
assume(b>0);
z = a + sqrt(-1)*b;
zabs = abs(z)

Results in:

zabs =

abs(a + b*1i)

I was expecting zabs = (a^2 +b^2)^(1/2). How do I get the result I want?

Patrick

Answer 1

[Walter Roberson]

rewrite(zabs, sqrt)

[Raptrick]

Thanks :)