/**** Decompose.h - Basic declarations ****/
#ifndef INCLUDED_DECOMPOSE
#define INCLUDED_DECOMPOSE
typedef struct {float x, y, z, w;} Quat; /* Quaternion */
enum QuatPart {X, Y, Z, W};
typedef Quat HVect; /* Homogeneous 3D vector */
typedef float HMatrix[4][4]; /* Right-handed, for column vectors */
typedef struct {
    HVect t;    /* Translation components */
    Quat  q;    /* Essential rotation     */
    Quat  u;    /* Stretch rotation   */
    HVect k;    /* Stretch factors    */
    float f;    /* Sign of determinant    */
} AffineParts;
float polar_decomp(HMatrix M, HMatrix Q, HMatrix S);
HVect spect_decomp(HMatrix S, HMatrix U);
Quat snuggle(Quat q, HVect *k);
void decomp_affine(HMatrix A, AffineParts *parts);
void invert_affine(AffineParts *parts, AffineParts *inverse);
#endif