元の三角形の頂点の座標から中点三角形の頂点の座標を計算する関数のプロトタイプ宣言の例
void medial_triangle(double xA, double yA, double xB, double yB, double xC, double yC, double *xAp, double *yAp, double *xBp, double *yBp, double *xCp, double *yCp);
void medial_triangle(const double reference[6], double central[6]);
void medial_triangle(const double reference[3][2], double central[3][2]);
struct point { double x, y; }; struct triangle { struct point A, B, C; }; struct triangle medial_triangle(struct triangle reference);
struct point { double x, y; }; struct triangle { struct point A, B, C; }; void medial_triangle(const struct triangle *reference, struct triangle *central);
struct point { double coordinates[2]; }; struct triangle { struct point vertices[3]; }; struct triangle medial_triangle(struct triangle reference);
struct point { double coordinates[2]; }; struct triangle { struct point vertices[3]; }; void medial_triangle(const struct triangle *reference, struct triangle *central);