int GiD_fWriteElementMat(GiD_FILE fd, int id, int nid[]);

int GiD_fWriteSphereMat(GiD_FILE fd, int id, int nid, double r, int mat);

int GiD_fWriteCircleMat(GiD_FILE fd, int id, int nid, double r, double nx, double ny, double nz, int mat);

Description: Similar to GiD_WriteElement, but the last aditional integer

on nid correspond to a material number.