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FloatApprox

approx. of rational number of the form M*2^E

Syntax
FloatApprox(X: INT|RAT|RINGELEM, PrecBits: INT): RAT

Description
This function computes an approximation of the form M*2^E to a rational number X where the mantissa satisfies 2^(B-1) <= |M| < 2^B-1 where B is the specified bit precision. It gives 0 when applied to 0.

The updated version of this function is not backward compatible with the old one; you must replace the 2nd arg by the number of bits you want in the mantissa (see ILogBase ). The old fn is obsolescent and is now called FloatApprox10 .

Example
/**/  FloatApprox(1/3, 10);
683/2048

/**/  FloatApprox(1/3, 20);
699051/2097152

/**/  FloatApprox(123456789,8);
123207680

See Also