CoCoA:MantissaAndExponent

MantissaAndExponent

convert rational number to a float

Description

This function converts a rational number into a Record with

components named Mantissa and Exponent. The value of the Exponent

field is the unique integer E such that <formula>1 <less_eq/> X*10^E <less_eq/> 10</formula>, and the value of Mantissa is the nearest integer to <formula>(X*10^E)*10^(Prec-1)</formula>. As an exception the case of X=0 always produces zero values for both components of the record.

Example

  FloatStr(1/2);         -- trailing zeroes are not suppressed
5.000000000*10^(-1)
-------------------------------
  MantissaAndExponent(1/2,3);           --  1/2 = 5.00*10^(-1)
Record[Exponent = -1, Mantissa = 500]
-------------------------------
  MantissaAndExponent(0.9999, 3);       --  0.9999 rounds up to give 1.00
Record[Exponent = 0, Mantissa = 100]
-------------------------------

Syntax

MantissaAndExponent(X:RAT, Prec:INT):RECORD

DecimalStr

FloatApprox

FloatStr

   <type>rat</type>
   <type>string</type>