id	summary	reporter	owner	description	type	status	milestone	component	version	severity	resolution	keywords	cc
8326	returned value of pow() is wrong if argument-variable is reused to accept.	pjtsu	John Maddock	"If argument-variable is reuse directly, pow(2, 10) returns 1.[[BR]]
Sample code is the following.

{{{

#include <iostream>
#include <iomanip>
#include <boost/math/special_functions/beta.hpp>
#include <boost/multiprecision/cpp_dec_float.hpp>

int main()
{
	typedef boost::multiprecision::number<boost::multiprecision::cpp_dec_float<50> > MY_FLOAT_TYPE;
	const double var1 = 2;
	const double var2 = 10;
	
	// OK (equal to 1024)
	{
		MY_FLOAT_TYPE a = var1;
		MY_FLOAT_TYPE b = var2;
		MY_FLOAT_TYPE c = pow(a, b);
		std::cout << ""result1="" << c << std::endl;
		a = c; // reusing variable 'a' indirectly.
		std::cout << ""result2="" << a << std::endl;
	}

	// NG (not equal to 1024)
	{
		MY_FLOAT_TYPE a = var1;
		MY_FLOAT_TYPE b = var2;
		a = pow(a, b); // reusing variable 'a' directly.
		std::cout << ""result3="" << a << std::endl;
	}
	
	return 0;
}

}}}

Output is the following.
{{{
result1=1024
result2=1024
result3=1
}}}

Incidentally, output of pow(2, 0.5) is the following. Similar problem happened.
{{{
result1=1.41421
result2=1.41421
result3=1.18921
}}}

I found this problem on Visual Studio 2010 and Linux gcc 4.4.7.[[BR]]
I found similar problem with '''mpf_float''' on Linux gcc 4.4.7.[[BR]]
"	Bugs	closed	To Be Determined	multiprecision	Boost 1.53.0	Problem	fixed