up previous next
MantissaAndExponent10

convert rational number to a float

Syntax
MantissaAndExponent10(X: INT|RAT|RINGELEM, Prec: INT): RECORD

Description
This function converts a rational number into a RECORD with components named exponent , mantissa and NumDigits .

If X=0 , all fields of the record are set to zero.

For non-zero X the fields give the best representation of the form M*10^E where M has Prec decimal digits. The value of NumDigits is simply Prec . The value of exponent is FloorLog10(X) , plus 1 if the mantissa "overflows". The value of mantissa is an integer M satisfying 10^(Prec-1) <= |M| < 10^Prec-1

Example
/**/  MantissaAndExponent10(1/2,3);       --  1/2 = 5.00*10^(-1)
record[NumDigits := 3, exponent := -1, mantissa := 500]

/**/  MantissaAndExponent10(0.99999, 4);   --  0.99999 rounds up to give 1.000
record[NumDigits := 4, exponent := 0, mantissa := 1000]

See Also