xmax.c

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#include <stdlib.h>

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

/****************************************************************
max(x0,x1,...,xn) returns maximum value
****************************************************************/

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

    if (argc < 1)
        return E_ARG_LO;

    for (i = 1; i <= argc; i++)
        if (argt[i] != argt[0])
            return E_ARG_TYPE;

    switch (argt[0]) {
    case CELL_TYPE:
        {
            CELL *res = args[0];
            CELL **argz = (CELL **) args;

            for (i = 0; i < columns; i++) {
                int nul = 0;
                CELL max;

                for (j = 1; j <= argc; j++)
                    if (IS_NULL_C(&argz[j][i]))
                        nul = 1;
                    else if (j == 1)
                        max = argz[j][i];
                    else if (max < argz[j][i])
                        max = argz[j][i];
                if (nul)
                    SET_NULL_C(&res[i]);
                else
                    res[i] = max;
            }
            return 0;
        }
    case FCELL_TYPE:
        {
            FCELL *res = args[0];
            FCELL **argz = (FCELL **) args;

            for (i = 0; i < columns; i++) {
                int nul = 0;
                FCELL max;

                for (j = 1; j <= argc; j++)
                    if (IS_NULL_F(&argz[j][i]))
                        nul = 1;
                    else if (j == 1)
                        max = argz[j][i];
                    else if (max < argz[j][i])
                        max = argz[j][i];
                if (nul)
                    SET_NULL_F(&res[i]);
                else
                    res[i] = max;
            }

            return 0;
        }
    case DCELL_TYPE:
        {
            DCELL *res = args[0];
            DCELL **argz = (DCELL **) args;

            for (i = 0; i < columns; i++) {
                int nul = 0;
                DCELL max;

                for (j = 1; j <= argc; j++)
                    if (IS_NULL_D(&argz[j][i]))
                        nul = 1;
                    else if (j == 1)
                        max = argz[j][i];
                    else if (max < argz[j][i])
                        max = argz[j][i];
                if (nul)
                    SET_NULL_D(&res[i]);
                else
                    res[i] = max;
            }

            return 0;
        }
    default:
        return E_INV_TYPE;
    }
}