Can someone tell me where is the problem? Matlab doesnt want to show me the real and the imag part of equation

>> syms A B d l >> real(0.98196*A*((-2+5i)^(d+l))+(6.0799*(-2+5i)^(1+l))+(40*(-2+5i)^l)+0.98196*B)

ans =

40*real((- 2 + 5*i)^l) + (60799*real((- 2 + 5*i)^(l + 1)))/10000 + (24549*real((- 2 + 5*i)^(d + l)*A))/25000 + (24549*real(B))/25000

>> imag((0.98196*A*((-2+5i)^(d+l))+(6.0799*(-2+5i)^(1+l))+(40*(-2+5i)^l)+0.98196*B))

ans =

40*imag((- 2 + 5*i)^l) + (60799*imag((- 2 + 5*i)^(l + 1)))/10000 + (24549*imag((- 2 + 5*i)^(d + l)*A))/25000 + (24549*imag(B))/25000

>>

Answer 1

[Mischa Kim]

Stefan, the problem is that the real and imaginary parts depend on the values of the variables, of course. Let me illustrate with a simple example. Assume n is an integer:

 syms n
 x = i^n;
 imag(x)
 ans =
   imag(i^n)
 y = subs(x,n,3);  % i^1 = i, i^2 = -1, i^3 = -i
 imag(y)
 ans =
   -1

i^n can be either real, or, imaginary, depending on whether n is even, or, odd. So, in general, you will not get a numeric result for real and imaginary parts unless you numerically specify all variables involved.