So I declare a complex function r[w] and I want to create another function U[w] which is defined by the real part of r[w]. So I try to use the embedded Re[] function but it returns a weird expression.
r[w]=200/(I*w*(10*I*w + 1))
If I do ComplexExpand[r[w]] I get -(2000/(1 + 100 w^2)) - (200 I)/(w (1 + 100 w^2)).
So I know that U[w] should be -(2000/(1 + 100 w^2)).
But the Re[r[w]] function returns 200 Im[1/((1 + 10 I w) w)]. Simplifying this expression by using Simplify[] and FullSimplify[] wouldn't help (even assuming that w is Real).
So how do I get the real and the imaginary part of my complex function r[w]?
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