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| Syntax C/C++ | #include <xmath.h>
double log2( double x );
long double log2l( long double x ); |
| Pascal/Delphi | uses xmath;
function log2( x:Extended ): Extended;
function log2d( x:Double ): Double; |
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| Description | The logarithm of the argument to the basis 2 is calculated and the result returned. |
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| Error handling | A DOMAIN error with NAN ("not-a-number") as return value results from x < 0 (including −0). A SING error with -HUGE_VAL as return value results from x=0.
In C/C++, the handling of both errors can be modified via _matherr or _matherrl, resp. |
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| Return value | The binary logarithm of the argument is returned. |
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