rotmg.c

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/**************************************************************************************
* 2014/05/02 Saar
* 	fixed two bugs as reported by Brendan Tracey
*	Test with lapack-3.5.0	: OK
*
**************************************************************************************/


#include "common.h"
#ifdef FUNCTION_PROFILE
#include "functable.h"
#endif

#define  GAM     4096.e0
#define  GAMSQ   16777216.e0
#define  RGAMSQ  5.9604645e-8

#define  TWO 2.e0

#ifdef DOUBLE
#define ABS(x) fabs(x)
#else
#define ABS(x) fabsf(x)
#endif

#ifndef CBLAS

void NAME(FLOAT *dd1, FLOAT *dd2, FLOAT *dx1, FLOAT *DY1, FLOAT *dparam){

  FLOAT	dy1 = *DY1;

#else

void CNAME(FLOAT *dd1, FLOAT *dd2, FLOAT *dx1, FLOAT dy1, FLOAT *dparam){

#endif

	FLOAT du, dp1, dp2, dq2, dq1, dh11=ZERO, dh21=ZERO, dh12=ZERO, dh22=ZERO, dflag=-ONE, dtemp;

	if (*dd2 == ZERO || dy1 == ZERO)
	{
		dflag = -TWO;
		dparam[0] = dflag;
		return;
	}
		
	if(*dd1 < ZERO)
	{
		dflag = -ONE;
		dh11  = ZERO;
		dh12  = ZERO;
		dh21  = ZERO;
		dh22  = ZERO;

		*dd1  = ZERO;
		*dd2  = ZERO;
		*dx1  = ZERO;
	}
	else if ((*dd1 == ZERO || *dx1 == ZERO) && *dd2 > ZERO)
	{
		dflag = ONE;
		dh12 = 1;
		dh21 = -1;
		*dx1 = dy1;
		dtemp = *dd1;
		*dd1 = *dd2;
		*dd2 = dtemp;
	} 
	else
	{
		dp2 = *dd2 * dy1;
		dp1 = *dd1 * *dx1;
		dq2 =  dp2 * dy1;
		dq1 =  dp1 * *dx1;
		if(ABS(dq1) > ABS(dq2))
		{
			dh11  =  ONE;
			dh22  =  ONE;
			dh21 = -  dy1 / *dx1;
			dh12 =    dp2 /  dp1;

			du   = ONE - dh12 * dh21;
			dflag = ZERO;
			*dd1  = *dd1 / du;
			*dd2  = *dd2 / du;
			*dx1  = *dx1 * du;
			
		}
		else
		{
			if(dq2 < ZERO)
			{
				dflag = -ONE;

				dh11  = ZERO;
				dh12  = ZERO;
				dh21  = ZERO;
				dh22  = ZERO;

				*dd1  = ZERO;
				*dd2  = ZERO;
				*dx1  = ZERO;
			}
			else
			{
				dflag =  ONE;
				dh21  = -ONE;
				dh12  =  ONE;

				dh11  =  dp1 /  dp2;
				dh22  = *dx1 /  dy1;
				du    =  ONE + dh11 * dh22;
				dtemp = *dd2 / du;

				*dd2  = *dd1 / du;
				*dd1  = dtemp;
				*dx1  = dy1 * du;
			}
		}


		while ( *dd1 <= RGAMSQ && *dd1 != ZERO)
		{
			dflag = -ONE;
			*dd1  = *dd1 * (GAM * GAM);
			*dx1  = *dx1 / GAM;
			dh11  = dh11 / GAM;
			dh12  = dh12 / GAM;
		}
		while (ABS(*dd1) > GAMSQ) {
			dflag = -ONE;
			*dd1  = *dd1 / (GAM * GAM);
			*dx1  = *dx1 * GAM;
			dh11  = dh11 * GAM;
			dh12  = dh12 * GAM;
		}

		while (ABS(*dd2) <= RGAMSQ && *dd2 != ZERO) {
			dflag = -ONE;
			*dd2  = *dd2 * (GAM * GAM);
			dh21  = dh21 / GAM;
			dh22  = dh22 / GAM;
		}
		while (ABS(*dd2) > GAMSQ) {
			dflag = -ONE;
			*dd2  = *dd2 / (GAM * GAM);
			dh21  = dh21 * GAM;
			dh22  = dh22 * GAM;
		}

	}

	if(dflag < ZERO)
	{
		dparam[1] = dh11;
		dparam[2] = dh21;
		dparam[3] = dh12;
		dparam[4] = dh22;
	}
	else
	{
		if(dflag == ZERO)
		{
			dparam[2] = dh21;
			dparam[3] = dh12;
		}
		else
		{
			dparam[1] = dh11;
			dparam[4] = dh22;
		}
	}


	dparam[0] = dflag;
	return;
}