/* 
 *  M_APM  -  mapm5sin.c
 *
 *  Copyright (C) 1999 - 2007   Michael C. Ring
 *
 *  Permission to use, copy, and distribute this software and its
 *  documentation for any purpose with or without fee is hereby granted,
 *  provided that the above copyright notice appear in all copies and
 *  that both that copyright notice and this permission notice appear
 *  in supporting documentation.
 *
 *  Permission to modify the software is granted. Permission to distribute
 *  the modified code is granted. Modifications are to be distributed by
 *  using the file 'license.txt' as a template to modify the file header.
 *  'license.txt' is available in the official MAPM distribution.
 *
 *  This software is provided "as is" without express or implied warranty.
 */

/*
 *      $Id: mapm5sin.c,v 1.10 2007/12/03 01:26:16 mike Exp $
 *
 *      This file contains the functions that implement the sin (5x)
 *	and cos (4x) multiple angle relations
 *
 *      $Log: mapm5sin.c,v $
 *      Revision 1.10  2007/12/03 01:26:16  mike
 *      Update license
 *
 *      Revision 1.9  2002/11/03 21:50:36  mike
 *      Updated function parameters to use the modern style
 *
 *      Revision 1.8  2001/03/25 20:57:03  mike
 *      move cos_to_sin func in here
 *
 *      Revision 1.7  2000/05/04 23:50:21  mike
 *      use multiple angle identity 4 times of larger COS angles
 *
 *      Revision 1.6  1999/06/30 00:08:53  mike
 *      pass more decimal places to raw functions
 *
 *      Revision 1.5  1999/06/20 23:41:32  mike
 *      changed COS to use 4x multiple angle identity instead of 5x
 *
 *      Revision 1.4  1999/06/20 19:42:26  mike
 *      tweak number of dec places passed to sub-functions
 *
 *      Revision 1.3  1999/06/20 19:03:56  mike
 *      changed local static variables to MAPM stack variables
 *
 *      Revision 1.2  1999/05/12 21:30:09  mike
 *      replace local 5.0 with global
 *
 *      Revision 1.1  1999/05/10 20:56:31  mike
 *      Initial revision
 */

#include "m_apm_lc.h"

/****************************************************************************/
void	M_5x_sin(M_APM r, int places, M_APM x)
{
M_APM   tmp8, tmp9;

tmp8 = M_get_stack_var();
tmp9 = M_get_stack_var();

m_apm_multiply(tmp9, x, MM_5x_125R);        /* 1 / (5*5*5) */
M_raw_sin(tmp8, (places + 6), tmp9);
M_5x_do_it(tmp9, (places + 4), tmp8);
M_5x_do_it(tmp8, (places + 4), tmp9);
M_5x_do_it(r, places, tmp8);

M_restore_stack(2);
}
/****************************************************************************/
void	M_4x_cos(M_APM r, int places, M_APM x)
{
M_APM   tmp8, tmp9;

tmp8 = M_get_stack_var();
tmp9 = M_get_stack_var();

/* 
 *  if  |x| >= 1.0   use multiple angle identity 4 times
 *  if  |x|  < 1.0   use multiple angle identity 3 times
 */

if (x->m_apm_exponent > 0)
  {
   m_apm_multiply(tmp9, x, MM_5x_256R);        /* 1 / (4*4*4*4) */
   M_raw_cos(tmp8, (places + 8), tmp9);
   M_4x_do_it(tmp9, (places + 8), tmp8);
   M_4x_do_it(tmp8, (places + 6), tmp9);
   M_4x_do_it(tmp9, (places + 4), tmp8);
   M_4x_do_it(r, places, tmp9);
  }
else
  {
   m_apm_multiply(tmp9, x, MM_5x_64R);         /* 1 / (4*4*4) */
   M_raw_cos(tmp8, (places + 6), tmp9);
   M_4x_do_it(tmp9, (places + 4), tmp8);
   M_4x_do_it(tmp8, (places + 4), tmp9);
   M_4x_do_it(r, places, tmp8);
  }

M_restore_stack(2);
}
/****************************************************************************/
/*
 *     calculate the multiple angle identity for sin (5x)
 *
 *     sin (5x) == 16 * sin^5 (x)  -  20 * sin^3 (x)  +  5 * sin(x)  
 */
void	M_5x_do_it(M_APM rr, int places, M_APM xx)
{
M_APM   tmp0, tmp1, t2, t3, t5;

tmp0 = M_get_stack_var();
tmp1 = M_get_stack_var();
t2   = M_get_stack_var();
t3   = M_get_stack_var();
t5   = M_get_stack_var();

m_apm_multiply(tmp1, xx, xx);
m_apm_round(t2, (places + 4), tmp1);     /* x ^ 2 */

m_apm_multiply(tmp1, t2, xx);
m_apm_round(t3, (places + 4), tmp1);     /* x ^ 3 */

m_apm_multiply(t5, t2, t3);              /* x ^ 5 */

m_apm_multiply(tmp0, xx, MM_Five);
m_apm_multiply(tmp1, t5, MM_5x_Sixteen);
m_apm_add(t2, tmp0, tmp1);
m_apm_multiply(tmp1, t3, MM_5x_Twenty);
m_apm_subtract(tmp0, t2, tmp1);

m_apm_round(rr, places, tmp0);
M_restore_stack(5);
}
/****************************************************************************/
/*
 *     calculate the multiple angle identity for cos (4x)
 * 
 *     cos (4x) == 8 * [ cos^4 (x)  -  cos^2 (x) ]  +  1
 */
void	M_4x_do_it(M_APM rr, int places, M_APM xx)
{
M_APM   tmp0, tmp1, t2, t4;

tmp0 = M_get_stack_var();
tmp1 = M_get_stack_var();
t2   = M_get_stack_var();
t4   = M_get_stack_var();

m_apm_multiply(tmp1, xx, xx);
m_apm_round(t2, (places + 4), tmp1);     /* x ^ 2 */
m_apm_multiply(t4, t2, t2);              /* x ^ 4 */

m_apm_subtract(tmp0, t4, t2);
m_apm_multiply(tmp1, tmp0, MM_5x_Eight);
m_apm_add(tmp0, MM_One, tmp1);
m_apm_round(rr, places, tmp0);
M_restore_stack(4);
}
/****************************************************************************/
/*
 *   compute  r = sqrt(1 - a ^ 2).
 */
void	M_cos_to_sin(M_APM r, int places, M_APM a)
{
M_APM	tmp1, tmp2;

tmp1 = M_get_stack_var();
tmp2 = M_get_stack_var();

m_apm_multiply(tmp1, a, a);
m_apm_subtract(tmp2, MM_One, tmp1);
m_apm_sqrt(r, places, tmp2);
M_restore_stack(2);
}
/****************************************************************************/