sics/vector.c

/**
 * This is a little collection of vector functions for use with the UB
 * calculation routines. Therefore vectors are mapped onto the matrix
 * package. Strictly speaking all routines only work properly on 3D
 * vectors.
 *
 * copyright: see file COPYRIGHT
 *
 * Mark Koennecke, March 2005
 */
#include <stdlib.h>
#include <assert.h>
#include <math.h>
#include "vector.h"
#include "trigd.h"

/*----------------------------------------------------------------------*/
MATRIX makeVector()
{
  return mat_creat(3, 1, ZERO_MATRIX);
}

/*---------------------------------------------------------------------*/
MATRIX makeVectorInit(double val[3])
{
  int i;
  MATRIX result = NULL;

  result = makeVector();
  if (result == NULL) {
    return result;
  }
  for (i = 0; i < 3; i++) {
    result[i][0] = val[i];
  }
  return result;
}

/*---------------------------------------------------------------------*/
void vectorToArray(MATRIX v, double val[3])
{
  int i;

  assert(MatCol(v) == 3);
  for (i = 0; i < 3; i++) {
    val[i] = v[i][0];
  }
}

/*----------------------------------------------------------------------*/
void killVector(MATRIX v)
{
  mat_free(v);
}

/*----------------------------------------------------------------------*/
void vectorSet(MATRIX v, int idx, double value)
{
  assert(idx >= 0 && idx < 3);

  v[idx][0] = value;
}

/*----------------------------------------------------------------------*/
double vectorGet(MATRIX v, int idx)
{
  assert(idx >= 0 && idx < 3);

  return v[idx][0];
}

/*----------------------------------------------------------------------*/
double vectorLength(MATRIX v)
{
  assert(MatRow(v) == 3);

  return sqrt(v[0][0] * v[0][0] + v[1][0] * v[1][0] + v[2][0] * v[2][0]);
}

/*---------------------------------------------------------------------*/
void normalizeVector(MATRIX v)
{
  int i;
  double norm;

  norm = vectorLength(v);
  if (norm > .00001) {
    for (i = 0; i < 3; i++) {
      v[i][0] /= norm;
    }
  } else {
    for (i = 0; i < 3; i++) {
      v[i][0] = .0;
    }
  }
}

/*----------------------------------------------------------------------*/
double vectorDotProduct(MATRIX v1, MATRIX v2)
{
  double sum;
  int i;

  assert(MatRow(v1) == MatRow(v2));

  sum = .0;
  for (i = 0; i < MatRow(v1); i++) {
    sum += v1[i][0] * v2[i][0];
  }
  return sum;
}

/*----------------------------------------------------------------------*/
MATRIX vectorCrossProduct(MATRIX v1, MATRIX v2)
{
  MATRIX result;

  assert(MatRow(v1) == 3);
  assert(MatRow(v2) == 3);

  result = makeVector();
  if (result == NULL) {
    return NULL;
  }
  vectorSet(result, 0,
            vectorGet(v1, 1) * vectorGet(v2, 2) 
	    - vectorGet(v1,2) * vectorGet(v2, 1));
  vectorSet(result, 1,
            vectorGet(v1, 2) * vectorGet(v2, 0) 
	      - vectorGet(v1,0) * vectorGet(v2, 2));
  vectorSet(result, 2,
            vectorGet(v1, 0) * vectorGet(v2, 1) 
                - vectorGet(v1, 1) * vectorGet(v2, 0));
  return result;
}

/*-------------------------------------------------------------------------*/
MATRIX matFromTwoVectors(MATRIX v1, MATRIX v2)
{
  MATRIX a1, a2, a3, result;
  int i;

  a1 = mat_copy(v1);
  if (a1 == NULL) {
    return NULL;
  }
  normalizeVector(a1);

  a3 = vectorCrossProduct(v1, v2);
  if (a3 == NULL) {
    return NULL;
  }
  normalizeVector(a3);

  a2 = vectorCrossProduct(a1, a3);
  if (a2 == NULL) {
    return NULL;
  }

  result = mat_creat(3, 3, ZERO_MATRIX);
  if (result == NULL) {
    return NULL;
  }

  for (i = 0; i < 3; i++) {
    result[i][0] = vectorGet(a1, i);
    result[i][1] = vectorGet(a2, i);
    result[i][2] = vectorGet(a3, i);
  }
  killVector(a1);
  killVector(a2);
  killVector(a3);
  return result;
}

/*-----------------------------------------------------------------------*/
double angleBetween(MATRIX v1, MATRIX v2)
{
  double angle, angles;
  MATRIX v3 = NULL;

  angle = vectorDotProduct(v1, v2) / (vectorLength(v1) * vectorLength(v2));
  v3 = vectorCrossProduct(v1, v2);
  if (v3 != NULL) {
    angles = vectorLength(v3) / (vectorLength(v1) * vectorLength(v2));
    angle = Atan2d(angles, angle);
  } else {
    angle = Acosd(angle);
  }
  return angle;
}

/*----------------------------------------------------------------------*/
void scaleVector(MATRIX v, double scale)
{
  int i;

  for (i = 0; i < 3; i++) {
    v[i][0] *= scale;
  }
}