/* See {hr2_pmap_opt_similarity.h}. */
/* Last edited on 2024-09-05 13:47:48 by stolfi */

#define _GNU_SOURCE
#include <stdint.h>
#include <assert.h>
#include <math.h>
 
#include <bool.h>
#include <sign.h>
#include <r2.h>
#include <affirm.h>

#include <hr2_pmap_opt_similarity.h>

void hr2_pmap_encode_similarity(hr2_pmap_t *M, double y[])
  { double A00 = M->dir.c[0][0];
    
    y[0] = M->dir.c[0][1] / A00;
    y[1] = M->dir.c[0][2] / A00;
    y[2] = M->dir.c[1][1] / A00;
    y[3] = M->dir.c[1][2] / A00;
  }

void hr2_pmap_decode_similarity(double y[], sign_t sgn, hr2_pmap_t *M)
  { 
    M->dir.c[0][0] = 1.00;
    M->dir.c[0][1] = y[0];
    M->dir.c[0][2] = y[1];
    
    M->dir.c[1][0] = 0.00;
    M->dir.c[1][1] = y[2];
    M->dir.c[1][2] = y[3];

    M->dir.c[2][0] = 0.0;
    if (sgn > 0)
      { M->dir.c[2][1] = - M->dir.c[1][2];
        M->dir.c[2][2] = + M->dir.c[1][1];
      }
    else
      { M->dir.c[2][1] = + M->dir.c[1][2];
        M->dir.c[2][2] = - M->dir.c[1][1];
      }
      
    r3x3_inv(&(M->dir), &(M->inv));

    /* Just in case: */
    M->inv.c[1][0] = 0.0;
    M->inv.c[2][0] = 0.0;
  }