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Update documentation for Kernel#BigDecimal() digits argument [ci skip] #151

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Update documentation for Kernel#BigDecimal() digits argument [ci skip] #151

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5 changes: 2 additions & 3 deletions ext/bigdecimal/bigdecimal.c
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Original file line number Diff line number Diff line change
Expand Up @@ -2681,9 +2681,8 @@ VpNewVarArg(int argc, VALUE *argv)
* If it is a String, spaces are ignored and unrecognized characters
* terminate the value.
*
* digits:: The number of significant digits, as an Integer. If omitted or 0,
* the number of significant digits is determined from the initial
* value.
* digits:: The number of significant digits, as an Integer. This is required if
* +initial+ is a Float or Rational, and ignored otherwise.
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0 for digits has the special meaning that the number of significant digits is automatically determined from the given initial value. For a Rational initial value, for example, the resulting BigDecimal is determined on the value of BigDecimal.limit and the behavior of BigDecimal#div.

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OK. I wonder if there is a better way to word it. I want the documentation to explain that it does not have an effect in cases where you would expect it would:

BigDecimal(1.1234, 2)
# => 0.11e1
BigDecimal(Rational(11234,10000), 2)
# => 0.11e1
BigDecimal('1.1234', 2)
# => 0.11234e1

BigDecimal(11234.0, 2)
# => 0.11e5
BigDecimal(11234, 2)
# => 0.11234e5

*
* The actual number of significant digits used in computation is
* usually larger than the specified number.
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