sfmath can now work with complex numbers. Try something like
sfmath n1=100 type=complex output=”exp(I*x1)” | sfgraph screenratio=1 | xtpen
You cannot, however, mix float and complex files in the input. Use sfdd, sfrtoc, sfreal, sfimag and sfcmplx to convert between real and complex types.
sfmath n1=100 output=x1 | sfrtoc | sfmath output=”exp(I*input)” | sfgraph screenratio=1 | xtpen