xrand.c

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#include <stdlib.h>

#include <grass/config.h>
#include <grass/gis.h>
#include <grass/raster.h>
#include <grass/calc.h>

/****************************************************************
rand(lo,hi) random values between a and b
****************************************************************/

int f_rand(int argc, const int *argt, void **args)
{
    int i;

    if (argc < 2)
        return E_ARG_LO;
    if (argc > 2)
        return E_ARG_HI;

    switch (argt[0]) {
    case CELL_TYPE:
        {
            CELL *res = args[0];
            CELL *arg1 = args[1];
            CELL *arg2 = args[2];

            for (i = 0; i < columns; i++) {
                unsigned int x = (unsigned int)G_mrand48();
                int lo = arg1[i];
                int hi = arg2[i];

                if (lo > hi) {
                    int tmp = lo;

                    lo = hi;
                    hi = tmp;
                }
                res[i] = (lo == hi) ? lo : lo + x % (unsigned int)(hi - lo);
            }
            return 0;
        }
    case FCELL_TYPE:
        {
            FCELL *res = args[0];
            FCELL *arg1 = args[1];
            FCELL *arg2 = args[2];

            for (i = 0; i < columns; i++) {
                double x = G_drand48();
                FCELL lo = arg1[i];
                FCELL hi = arg2[i];

                if (lo > hi) {
                    FCELL tmp = lo;

                    lo = hi;
                    hi = tmp;
                }
                res[i] = (FCELL) (lo + x * (hi - lo));
            }
            return 0;
        }
    case DCELL_TYPE:
        {
            DCELL *res = args[0];
            DCELL *arg1 = args[1];
            DCELL *arg2 = args[2];

            for (i = 0; i < columns; i++) {
                double x = G_drand48();
                DCELL lo = arg1[i];
                DCELL hi = arg2[i];

                if (lo > hi) {
                    DCELL tmp = lo;

                    lo = hi;
                    hi = tmp;
                }
                res[i] = lo + x * (hi - lo);
            }
            return 0;
        }
    default:
        return E_INV_TYPE;
    }
}