OpenBLAS/kernel/arm/znrm2.c

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/**************************************************************************************
* 2013/09/13 Saar
*	 BLASTEST float		: OK
* 	 BLASTEST double	: OK
* 	 CTEST			: OK
* 	 TEST			: OK
*
**************************************************************************************/

#include "common.h"
#include <math.h>

#if defined(DOUBLE)

#define ABS fabs

#else

#define ABS fabsf

#endif



FLOAT CNAME(BLASLONG n, FLOAT *x, BLASLONG inc_x)
{
	BLASLONG i=0;
	FLOAT scale = 0.0;
	FLOAT ssq   = 1.0;
	BLASLONG inc_x2;
	FLOAT temp;

	if (n <= 0 || inc_x <= 0) return(0.0);

	inc_x2 = 2 * inc_x;

	n *= inc_x2;
	while(i < n)
	{

		if ( x[i] != 0.0 )
		{
			temp = ABS( x[i] );
			if ( scale < temp )
			{
				ssq = 1 + ssq * ( scale / temp ) * ( scale / temp );
				scale = temp ;
			}
			else
			{
				ssq += ( temp / scale ) * ( temp / scale );
			}

		}

		if ( x[i+1] != 0.0 )
		{
			temp = ABS( x[i+1] );
			if ( scale < temp )
			{
				ssq = 1 + ssq * ( scale / temp ) * ( scale / temp );
				scale = temp ;
			}
			else
			{
				ssq += ( temp / scale ) * ( temp / scale );
			}

		}


		i += inc_x2;
	}
	scale = scale * sqrt( ssq );
	return(scale);

}