While interpreting UDF. i get an error internal_error too few arguments specified (argument 2) What does this mean?

I guess you are using internal_error macro in your udf. Recheck it with the sample given in users guide. I guess you may not even need this internal_error macro(ur udf will work for ur purpose by removing this macro/loop also). If possible can you post your udf here.

This is the UDF/Uds Which gave me the error.

include "udf.h" enum { Ar, Ai, N_REQUIRED_UDS }; double cond = 1.5; double mu = 12.56e-7; double omega = 3e6;

DEFINE_ADJUST(Atheta_adjust, domain) { if (n_uds < N_REQUIRED_UDS) Internal Error ("not enough uds allocated"); }

DEFINE_SOURCE(Ar_source,c,t,ds,eqn) { ds[eqn] = mu*omega*cond; return mu*cond*omega* C_UDSI c,t,Ai); }

DEFINE_SOURCE(Ai_source,c,t,ds,eqn) { ds[eqn] = -mu*omega*cond; return -mu*cond*omega*C_UDSI(c,t,Ar); }

DEFINE_DIFFUSIVITY(Atheta_diffusivity,c,t,i) { return 1; }