hi Im using the guru interface so that I can work on different arrays. The restriction of guru interface are applied. 1. plan = fftw_plan_dft_r2c_1d(ndim, in, out, flags); //int flags = FFTW_PATIENT 2. fftw_execute_dft_r2c(plan, in, out); I have set the types correct for the arguments but I am not able to get the execution right.Im able to compile my code and run it. But I get incorrect results. Did anyone encoutner similar issues? Please let me know regards kiran