struct vec{float a[3];} /* A plain vector */;
struct tri {vec A[3];}  /* A tensor */;
struct vert{vec wh, mom; float mass;} /* All about a vertex */;
struct lt{float a,b,c,d,e,f;}  /* A lower triangular matrix */;
struct simp{lt sh; short v[4]; short mat;} /* All about a zone */;
struct link{short a, b;} /* Verticies to draw between */;
void rec_seg(int, int);
void physics(void); 
vert cvert(vec, float m);
void pr(vec);
vec operator*(float, vec); vec operator+(vec, vec); vec operator-(vec, vec); 
float px(float);
void init(void); void force(float);
void tent(int,int,int,int,int,int);
tri tp(tri);
vec operator*(lt, vec); vec cdvec(int, int); 
vec operator%(vec, vec); float operator*(vec, vec); 
extern vec zvec;
extern int damp; 
vec cvec(float i, float j, float k); tri ctri(vec, vec, vec);

extern link segs[]; extern int n_segs;
extern int cycle; extern float dt; extern int xx;
/* The guts */ extern vert u[]; extern simp s[]; extern int n_vert, n_seg;
/* Table of materials */ extern float mu[], lam[];
/* Material index while calling tent */ extern short material;