/**
 * This is a library of trigonmetric functions acting upon proper
 * angles and not radians. Lifted from the Risoe tascom code
 *
 * March 2005
 */
#include <math.h>
#include "trigd.h"

/* define constants */
#ifndef PI
#define PI              (3.1415926536)  /* pi */
#endif
#define DEGREE_RAD      (PI/180.0)      /* Radians per degree */
/*******************************************************************************/
double Sign(double d)
{
  if (d < .0) {
    return -1;
  } else {
    return 1;
  }
}

/*******************************************************************************
* Sinus of angle in degrees.
*******************************************************************************/
extern double Sind(double x)
{
  return (sin(x * DEGREE_RAD));
}

/*******************************************************************************
* Tangens of angle in degrees.
*******************************************************************************/
extern double Tand(double x)
{
  return (tan(x * DEGREE_RAD));
}

/*******************************************************************************
* cotangens of angle in degrees
*****************************************************************************/
extern double Cotd(double x)
{
  if (tan(x * DEGREE_RAD) > .00001) {
    return (1. / tan(x * DEGREE_RAD));
  } else {
    return 0;
  }
}

/*******************************************************************************
* Cosinus of angle in degrees.
*******************************************************************************/
extern double Cosd(double x)
{
  return (cos(x * DEGREE_RAD));
}

/*******************************************************************************
* Atan of angle in degrees.
*******************************************************************************/
extern double Atand(double x)
{
  double data;

  data = (atan(x) / DEGREE_RAD);
  return (data);
}

/*******************************************************************************
* Atan of angle in degrees.
*******************************************************************************/
extern double Atan2d(double x, double y)
{
  double data;

  data = (atan2(x, y) / DEGREE_RAD);
  return (data);
}

/*******************************************************************************
* Atan2 of angle in degrees.
*******************************************************************************/
extern double Atand2(double x)
{
  double data;

  data = (atan(x) / DEGREE_RAD);
  return (data);
}

/*******************************************************************************
* Acos of angle in degrees.
*******************************************************************************/
extern double Acosd(double x)
{
  double data;

  data = acos(x) / DEGREE_RAD;
  return (data);
}

/*******************************************************************************
* Asin of angle in degrees.
*******************************************************************************/
extern double Asind(double x)
{
  double data;

  data = x * x;
  if (data == 1.0)
    return (180.00 - Sign(x) * 90.00);
  else if (data > 1) {
    return (0);
  } else
    return (Atand(x / sqrt(1 - data)));

}