fixed: in Big::ToString_CreateNewMantissaAndExponent() changed the formula:
new_exp_ = [log base (2^exponent)] + 1 now the part '+ 1' is only made when the logarithm is positive and with fraction if the value is negative we can only skip the fraction, previously we lost some last digits from the new mantissa Consider this binary value (32 bit mantissa): (bin)1.0000000000000000000000000000011 previously ToString() gave 1, now we have: 1.000000001 git-svn-id: svn://ttmath.org/publicrep/ttmath/trunk@274 e52654a7-88a9-db11-a3e9-0013d4bc506e
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10
CHANGELOG
10
CHANGELOG
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@ -1,4 +1,4 @@
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Version 0.9.1 prerelease (2009.12.25):
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Version 0.9.1 prerelease (2009.12.28):
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* fixed: the parser didn't use characters for changing the base (# and &)
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those characters were skipped
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(this bug was introduced in 0.9.0)
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@ -6,6 +6,14 @@ Version 0.9.1 prerelease (2009.12.25):
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operator ^ (powering) is right-associative:
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sample: 2^3^4 is equal 2^(3^4) and it is: 2.41e+24
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previously was: 2^3^4 = (2^3)^4 = 4096
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* fixed: in Big::ToString_CreateNewMantissaAndExponent() changed the formula:
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new_exp_ = [log base (2^exponent)] + 1
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now the part '+ 1' is only made when the logarithm is positive and with fraction
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if the value is negative we can only skip the fraction, previously
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we lost some last digits from the new mantissa
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Consider this binary value (32 bit mantissa):
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(bin)1.0000000000000000000000000000011
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previously ToString() gave 1, now we have: 1.000000001
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* added: IEEE 754 half-to-even rounding (bankers' rounding) to the following
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floating point algorithms: Big::Add, Big::Sub, Big::Mul, Big::Div
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* added: to Big::ToString() - additional rounding when conv.base_round is used
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@ -3312,8 +3312,11 @@ private:
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2^exponent <= base^new_exp
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new_exp >= log base (2^exponent) <- logarithm with the base 'base' from (2^exponent)
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but we need 'new'exp' as integer then we take:
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new_exp = [log base (2^exponent)] + 1 <- where [x] means integer value from x
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but we need new_exp as integer then we test:
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if new_exp is greater than zero and with fraction we add one to new_exp
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new_exp = new_exp + 1 (if new_exp>0 and with fraction)
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and at the end we take the integer part:
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new_exp = int(new_exp)
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*/
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template<class string_type, class char_type>
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uint ToString_CreateNewMantissaAndExponent( string_type & new_man, const Conv & conv,
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@ -3351,12 +3354,21 @@ private:
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temp.mantissa.SetOne();
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c += temp.Standardizing();
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// new_exp_ = [log base (2^exponent)] + 1
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// new_exp_ = log base (2^exponent)
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// if new_exp_ is positive and with fraction then we add one
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Big<exp+1,man> new_exp_;
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c += new_exp_.ToString_Log(temp, conv.base); // this logarithm isn't very complicated
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if( !new_exp_.IsSign() && !new_exp_.IsInteger() )
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{
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// new_exp_ > 0 and with fraction
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temp.SetOne();
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c += new_exp_.Add( temp );
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}
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// new_exp_ = int(new_exp_)
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new_exp_.SkipFraction();
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temp.SetOne();
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c += new_exp_.Add( temp );
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// because 'base^new_exp' is >= '2^exponent' then
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// because base is >= 2 then we've got:
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