In reply to saketa:
All DPI routines you import must be linked into a shared object (Windows: *.dll, Linux: *.so). The message about not finding it in the uvm_dpi.dll isbecause that was the only shared object provided. Math library functions like sin,cos, log need to be compiled into another shared object and loaded into the simulator. See this link for an example. The actual commands needed to compile this are tool/platform specific, and you will need to read the user manual of your tool, or contact your tool vendor directly for support.