Strange return behaviour in UDF (bug?)

[Richard Massa]

Hi there,

I'm getting a strange behaviour when returning a value from my user defined
function.  When I print the return value inside of the function, I get one 
answer (the correct one), however mysql reports a different value all together.
Is this my programming error or a mysql bug?

Here's what I'm seeing:

In mysql:

+-------------------------------------------------------------------------+
| ddist(m.x, m.y, m.z, n.x, n.y, n.z, 30.0893021, 30.3757286, 32.6442299) |
+-------------------------------------------------------------------------+
|                                                                    0.72 |
|                                                                    0.66 |
|                                                                    0.61 |
|                                                                    0.47 |
+-------------------------------------------------------------------------+

my hostname.err logfile where I print debugging info:

result: 33.048230
result: 9.203189
result: 12.836390
result: 9.615359

Here's the source code for my program

#include <stdio.h>
#include <string.h>
#include <my_global.h>
#include <my_sys.h>
#include <mysql.h>
#include <m_ctype.h>

#ifdef HAVE_DLOPEN

extern "C" {

my_bool ddist_init (UDF_INIT *initid, UDF_ARGS *args, char *message);
void ddist_deinit (UDF_INIT *initid);
double ddist (UDF_INIT *initid, UDF_ARGS *args, char *is_null, char *error);

}

void ddist_deinit(UDF_INIT *initid){}

my_bool ddist_init(UDF_INIT *initid, UDF_ARGS *args, char *message)
        {
                initid->decimals=2;           // We want 2 decimals in the result
                initid->max_length=6;         // 3 digits + . + 2 decimals

                return 0;
/*
                int i=0; // counter

                if (!args->arg_count || args->arg_count != 9) 
                {
                        strcpy(message,"dist must have exactly nine arguments");
                        return 2;
                }
                
                for ( i=0;i<6;i++ )
                {
                        if ( args->arg_type[i] != REAL_RESULT )
                                strcpy( message, "dist must be passed six real 
numbers");
                                return 2;
                }
*/
        }

double ddist(UDF_INIT *initid, UDF_ARGS *args, char *is_null, char *error)
{
                double xi, yi, zi, xj, yj, zj, cubex, cubey, cubez ; //variables for 
arguments
                int shiftx, shifty, shiftz; // temp variables
                double rijx, rijy, rijz; // temp variables
                double result; // result

                xi = *((double*)args->args[0]);
                yi = *((double*)args->args[1]);
                zi = *((double*)args->args[2]);
                xj = *((double*)args->args[3]);
                yj = *((double*)args->args[4]);
                zj = *((double*)args->args[5]);

                cubex = *((double*)args->args[6]);
                cubey = *((double*)args->args[7]);
                cubez = *((double*)args->args[8]);

                shiftx = int( rint( (xi-xj)/cubex ));
                shifty = int( rint( (yi-yj)/cubey ));
                shiftz = int( rint( (zi-zj)/cubez ));
                fprintf(stderr,"sx=%d, sy=%d, sz=%d, cx=%f, cy=%f, cz=%f, xi=%f, 
yi=%f, zi=%f, xj=%f, yj=%f, 
zj=%f\n",shiftx,shifty,shiftz,cubex,cubey,cubez,xi,yi,zi,xj,yj,zj);

                rijx = xi-xj-cubex*shiftx;
                rijy = yi-yi-cubey*shifty;
                rijz = zi-zj-cubez*shiftz;
                fprintf(stderr,"rijx=%f,rijy=%f,rijz=%f\n",rijx,rijy,rijz);

                result = sqrt( (rijx*rijx) + (rijy*rijy) + (rijz*rijz) );

                fprintf(stderr,"test: %f\n",(rijz*rijz));
                fprintf(stderr,"result: %f\n",result);
                return result;
}

#endif /* HAVE_DLOPEN */

Here's what I'm using to compile:

g++ -O3 -DDBUG_OFF -fno-implicit-templates -fno-exceptions -fno-rtti -shared
-I/usr/include/mysql -rdynamic dist.cc -o dist.so

Anyone have any ideas?

Thanks,
Richard

-- 
"a professional is simply one who gets paid for doing what an amateur does for
love."
                                                                                       
                                                 -- Ursula K. Le Guin

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