udf problem
 

to check variable in source file, I make write to an output file and CH4 mass fraction is written as 1.#QNANe+000 in the output file ,but I entered it 0.43 in the fluent, why this happened so? how can I fix this? and How can I change mass fraction to mole fraction? is there a shortcut to do this?

DEFINE_VR_RATE(Reaction_Rate,c,t,r,mole_weight,spe cies_mf,Rate,rr_t) { real T = C_T(c, t); real Pb = C_P(c, t); real yH2O = species_mf[0]; real yCH4 = species_mf[1]; real yCO = species_mf[2]; real yH2 = species_mf[3];

fp= fopen("output.txt","w"); fprintf(fp," yCH4 rate values: %9.8e %9.8e\n", yCH4, Rate); fclose( fp );