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E added. Typo corrected.

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git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@4411 b2dd03c8-39d4-4d8f-98ff-823fe69b080e
This commit is contained in:
shigek 2003-08-19 14:16:09 +00:00
parent c41b3b96ab
commit caf213d9ad
1 changed files with 22 additions and 3 deletions
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25
ext/bigdecimal/lib/bigdecimal/math.rb
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@ -7,6 +7,7 @@
# exp (x, prec)
# log (x, prec)
# PI (prec)
# E (prec) == exp(1.0,prec)
#
# where:
# x ... BigDecimal number to be computed.
@ -51,7 +52,7 @@ module BigMath
end
def cos(x, prec)
raise ArgumentError, "Zero or negative precision for sin" if prec <= 0
raise ArgumentError, "Zero or negative precision for cos" if prec <= 0
return BigDecimal("NaN") if x.infinite? || x.nan?
n = prec + BigDecimal.double_fig
one = BigDecimal("1")
@ -76,7 +77,7 @@ module BigMath
end
def atan(x, prec)
raise ArgumentError, "Zero or negative precision for sin" if prec <= 0
raise ArgumentError, "Zero or negative precision for atan" if prec <= 0
return BigDecimal("NaN") if x.infinite? || x.nan?
raise ArgumentError, "x.abs must be less than 1.0" if x.abs>=1
n = prec + BigDecimal.double_fig
@ -96,7 +97,7 @@ module BigMath
end
def exp(x, prec)
raise ArgumentError, "Zero or negative precision for sin" if prec <= 0
raise ArgumentError, "Zero or negative precision for exp" if prec <= 0
return BigDecimal("NaN") if x.infinite? || x.nan?
n = prec + BigDecimal.double_fig
one = BigDecimal("1")
@ -174,4 +175,22 @@ module BigMath
end
pi
end
def E(prec)
raise ArgumentError, "Zero or negative precision for E" if prec <= 0
n = prec + BigDecimal.double_fig
one = BigDecimal("1")
y = one
d = y
z = one
i = 0
while d.nonzero? && ((m = n - (y.exponent - d.exponent).abs) > 0)
m = BigDecimal.double_fig if m < BigDecimal.double_fig
i += 1
z *= i
d = one.div(z,m)
y += d
end
y
end
end