Hello, I am making the following adjustment to the user defined function template files . I am using MonetDB-11.15.15 built from source on Ubuntu 12.04. I have added to the following files in the ./sql/backends/monet5/UDF directory as shown: 80_udf.sql create function sumProb(prob1 double, prob2 double) returns double external name udf.sumProb; udf.mal module udf; command sumProb(prob1:dbl,prob2:dbl):dbl address UDFSumProb comment "sum two probabilities"; udf.c str UDFSumProb(dbl * res, dbl * prob1, dbl * prob2) { *res = *prob1 + *prob2; return MAL_SUCCEED; } udf.h udf_export str UDFSumProb(dbl * res, dbl * prob1, dbl * prob2); I did a configure/make/make install and tried the following call in mclient: declare a, b,c double; set a= 0.1; set b= 0.2; select c=jsdistance(a,b); and get the error: TypeException:user.s2_1[8]:'udf.sumprob' undefined in: _12:any := udf.sumprob(_8:dbl, _11:dbl) program contains errors