typedef struct SO2DPlot_Triangle_Val
  { double P;
    double Q;
    double R;
  } SO2DPlot_Triangle_Val;

typedef struct SO2DPlot_Triangle
  { double P[PDIM];
    double Q[PDIM];
    double R[PDIM];
  } SO2DPlot_Triangle;

typedef struct SO2DPlot_Triangle_vec 
  { nat nel; 
    SO2DPlot_Triangle*el;
  } SO2DPlot_Triangle_vec;

/* Vectors of Triangle */

SO2DPlot_Triangle_vec SO2DPlot_Triangle_vec_new(nat nel);
#define SO2DPlot_Triangle_vec_expand(nv,index) \
  vec_expand(vec_cast_ref(nv), index, sizeof(SO2DPlot_Triangle))
#define SO2DPlot_Triangle_vec_trim(nv,nel) \
  vec_trim(vec_cast_ref(nv), nel, sizeof(SO2DPlot_Triangle))

/* Arrays of {SO2DPlot_Triangle}: */

SO2DPlot_Triangle_vec SO2DPlot_Triangle_vec_new(nat nel)
  { /* This is not a macro only because gcc does not allow cast of struct: */
    vec_t v = vec_new(nel, sizeof(SO2DPlot_Triangle));
    SO2DPlot_Triangle_vec r;
    r.nel = v.nel; r.el = (SO2DPlot_Triangle*)v.el;
    return r;
  }