# usecases/c/UsesCase_MEDinterp_1.c

    /*  This file is part of MED.
     *
     *  COPYRIGHT (C) 1999 - 2012  EDF R&D, CEA/DEN
     *  MED is free software: you can redistribute it and/or modify
     *  it under the terms of the GNU Lesser General Public License as published by
     *  the Free Software Foundation, either version 3 of the License, or
     *  (at your option) any later version.
     *
     *  MED is distributed in the hope that it will be useful,
     *  but WITHOUT ANY WARRANTY; without even the implied warranty of
     *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
     *  GNU Lesser General Public License for more details.
     *
     *  You should have received a copy of the GNU Lesser General Public License
     *  along with MED.  If not, see <http://www.gnu.org/licenses/>.
     */

    /*
     * Interp use case 1 : write an interpolation family
     * In this example, the interpolation family can be used with
     * the TEMPERATURE field of UsesCase_MEDfield_10 use case
     */

    #include <med.h>
    #define MESGERR 1
    #include <med_utils.h>

    #include <string.h>

    int main (int argc, char **argv) {
      med_idt fid;
      char interpname[MED_NAME_SIZE+1] = "MED_TRIA3 interpolation family";
      const med_int nvariable=2;
      const med_int maxdegree=1;
      const med_int nmaxcoefficient=3;
      const med_int         ncoefficient1_1 = 3;
      const med_int   const power1_1[]         = {0,0,1,0,0,1};
      const med_float const coefficient1_1[]   = {1,-1,-1};

      const med_int         ncoefficient1_2 = 1;
      const med_int   const power1_2[]         = {1,0};
      const med_float const coefficient1_2[]   = {1};

      const med_int         ncoefficient1_3 = 1;
      const med_int   const power1_3[]         = {0,1};
      const med_float const coefficient1_3[]   = {1};
      int ret=-1;

      /* file creation */
      fid = MEDfileOpen("UsesCase_MEDinterp_1.med",MED_ACC_CREAT);
      if (fid < 0) {
        MESSAGE("ERROR : file creation ...");
        goto ERROR;
      }

      /* Family interpolation creation :
         - reference element = MED_TRIA3
         - integration points of UsesCase_MEDfield_10 use case
         are used to build the interpolation
         - basis functions are P1(X)= 1-X1-X2, P2(X)= X1, P3(X)= X2
       */
      if (MEDinterpCr(fid, interpname, MED_TRIA3, MED_FALSE, nvariable, maxdegree, nmaxcoefficient) < 0) {
        MESSAGE("ERROR : interpolation family creation ...");
        goto ERROR;
      }

      /* Basis functions creation */
      if (MEDinterpBaseFunctionWr(fid,interpname,1,ncoefficient1_1,power1_1,coefficient1_1) < 0) {
        MESSAGE("ERROR : first base function creation ...");
        goto ERROR;
      }

      if (MEDinterpBaseFunctionWr(fid,interpname,2,ncoefficient1_2,power1_2,coefficient1_2) < 0) {
        MESSAGE("ERROR : second base function creation ...");
        goto ERROR;
      }

      if (MEDinterpBaseFunctionWr(fid,interpname,3,ncoefficient1_3,power1_3,coefficient1_3) < 0) {
        MESSAGE("ERROR : third base function creation ...");
        goto ERROR;
      }

      ret=0;
     ERROR:

      /* close file */
      if (MEDfileClose(fid) < 0) {
        MESSAGE("ERROR : close file ...");
        ret=-1;
      }

      return ret;
    }