In reply to chr_sue:
thank you chr_sue now it work, and i had replaced the C sin function by a SV sin approximation function
but a fatal error has occured:
** Fatal: vl_unpack_regbit: Cannot handle type.
# Time: 1 ns Iteration: 0 Process: /top/sine_if1/cb File: D:/sigma_delta_SV/FirstSDM.sv
# Fatal error at an unknown location