// filename:c2011-F-10-3-4-ex.c
// original examples and/or notes:
// 		(c) ISO/IEC JTC1 SC22 WG14 N1570, April 12, 2011
// http://www.open-std.org/jtc1/sc22/wg14/www/docs/n1570.pdf
// 			C2011 Annex F.10.3.4 The frexp functions
// compile and output mechanism:
// 		(c) Ogawa Kiyoshi, kaizen@gifu-u.ac.jp, January.04, 2014
// compile errors and/or wornings:
// 1	(c) Apple LLVM version 4.2 (clang-425.0.27) (based on LLVM 3.2svn)
// 			Target: x86_64-apple-darwin11.4.2 //Thread model: posix
// 		(c) LLVM 2003-2009 University of Illinois at Urbana-Champaign.
// 2    gcc-4.9 (GCC) 4.9.0 20131229 (experimental)
//      Copyright (C) 2013 Free Software Foundation, Inc.
#include <stdio.h>
#include <math.h>
#define MAX 5
double frexp_a(double value, int *exp){
	*exp = (value == 0) ? 0 : (int)(1 + logb(value));
	printf("logb(%f)=%d, scalbn(value, -(%d))=%f \n", value, (int)(1 + logb(value)), *exp, scalbn(value, -(*exp)));
	return scalbn(value, -(*exp));
}
int main(void)
{
   	int exp,exp_a;
	double value[]={3.14159,-2.5,0,FP_INFINITE,FP_NAN },ret,ret_a;
	for(int i=0;i<MAX;i++){
   		ret = frexp( value[i], &exp );
		ret_a = frexp_a( value[i], &exp_a );
   	printf("frexp( %f, exp ) = %f, exp = %d, frex_a(,)=%f exp_a=%d, true=%d \n", value[i], ret, exp,ret_a,exp_a, ((ret==ret_a)&(exp==exp_a)) );
	} 
	printf("Annex F.10.3.4 The frexp functions \n");
}

// 1. output LLVM 3.2 & GCC4.9
//logb(3.141590)=2, scalbn(value, -(2))=0.785397
//frexp( 3.141590, exp ) = 0.785397, exp = 2, frex_a(,)=0.785397 exp_a=2, true=1 
//logb(-2.500000)=2, scalbn(value, -(2))=-0.625000  
//frexp( -2.500000, exp ) = -0.625000, exp = 2, frex_a(,)=-0.625000 exp_a=2, true=1 
//logb(0.000000)=-2147483648, scalbn(value, -(0))=0.000000 
//frexp( 0.000000, exp ) = 0.000000, exp = 0, frex_a(,)=0.000000 exp_a=0, true=1 
//logb(2.000000)=2, scalbn(value, -(2))=0.500000 
//frexp( 2.000000, exp ) = 0.500000, exp = 2, frex_a(,)=0.500000 exp_a=2, true=1 
//logb(1.000000)=1, scalbn(value, -(1))=0.500000 
//frexp( 1.000000, exp ) = 0.500000, exp = 1, frex_a(,)=0.500000 exp_a=1, true=1 
//Annex F.10.3.4 The frexp functions 
// logb(3.141590)=2, scalbn(value, -(-266631570))=1072243193