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-rw-r--r--ext/bigdecimal/lib/bigdecimal/math.rb71
1 files changed, 56 insertions, 15 deletions
diff --git a/ext/bigdecimal/lib/bigdecimal/math.rb b/ext/bigdecimal/lib/bigdecimal/math.rb
index 7289661..4504ccb 100644
--- a/ext/bigdecimal/lib/bigdecimal/math.rb
+++ b/ext/bigdecimal/lib/bigdecimal/math.rb
@@ -20,30 +20,40 @@ require 'bigdecimal'
#
# Example:
#
-# require "bigdecimal"
# require "bigdecimal/math"
#
# include BigMath
#
# a = BigDecimal((PI(100)/2).to_s)
-# puts sin(a,100) # -> 0.10000000000000000000......E1
+# puts sin(a,100) # => 0.10000000000000000000......E1
#
module BigMath
module_function
- # Computes the square root of x to the specified number of digits of
- # precision.
+ # call-seq:
+ # sqrt(decimal, numeric) -> BigDecimal
#
- # BigDecimal.new('2').sqrt(16).to_s
- # -> "0.14142135623730950488016887242096975E1"
+ # Computes the square root of +decimal+ to the specified number of digits of
+ # precision, +numeric+.
#
- def sqrt(x,prec)
+ # BigMath::sqrt(BigDecimal.new('2'), 16).to_s
+ # #=> "0.14142135623730950488016887242096975E1"
+ #
+ def sqrt(x, prec)
x.sqrt(prec)
end
- # Computes the sine of x to the specified number of digits of precision.
+ # call-seq:
+ # sin(decimal, numeric) -> BigDecimal
+ #
+ # Computes the sine of +decimal+ to the specified number of digits of
+ # precision, +numeric+.
+ #
+ # If +decimal+ is Infinity or NaN, returns NaN.
+ #
+ # BigMath::sin(BigMath::PI(5)/4, 5).to_s
+ # #=> "0.70710678118654752440082036563292800375E0"
#
- # If x is infinite or NaN, returns NaN.
def sin(x, prec)
raise ArgumentError, "Zero or negative precision for sin" if prec <= 0
return BigDecimal("NaN") if x.infinite? || x.nan?
@@ -77,9 +87,17 @@ module BigMath
neg ? -y : y
end
- # Computes the cosine of x to the specified number of digits of precision.
+ # call-seq:
+ # cos(decimal, numeric) -> BigDecimal
+ #
+ # Computes the cosine of +decimal+ to the specified number of digits of
+ # precision, +numeric+.
+ #
+ # If +decimal+ is Infinity or NaN, returns NaN.
+ #
+ # BigMath::cos(BigMath::PI(4), 16).to_s
+ # #=> "-0.999999999999999999999999999999856613163740061349E0"
#
- # If x is infinite or NaN, returns NaN.
def cos(x, prec)
raise ArgumentError, "Zero or negative precision for cos" if prec <= 0
return BigDecimal("NaN") if x.infinite? || x.nan?
@@ -113,9 +131,17 @@ module BigMath
y
end
- # Computes the arctangent of x to the specified number of digits of precision.
+ # call-seq:
+ # atan(decimal, numeric) -> BigDecimal
+ #
+ # Computes the arctangent of +decimal+ to the specified number of digits of
+ # precision, +numeric+.
+ #
+ # If +decimal+ is NaN, returns NaN.
+ #
+ # BigMath::atan(BigDecimal.new('-1'), 16).to_s
+ # #=> "-0.785398163397448309615660845819878471907514682065E0"
#
- # If x is NaN, returns NaN.
def atan(x, prec)
raise ArgumentError, "Zero or negative precision for atan" if prec <= 0
return BigDecimal("NaN") if x.nan?
@@ -144,7 +170,15 @@ module BigMath
y
end
- # Computes the value of pi to the specified number of digits of precision.
+ # call-seq:
+ # PI(numeric) -> BigDecimal
+ #
+ # Computes the value of pi to the specified number of digits of precision,
+ # +numeric+.
+ #
+ # BigMath::PI(10).to_s
+ # #=> "0.3141592653589793238462643388813853786957412E1"
+ #
def PI(prec)
raise ArgumentError, "Zero or negative argument for PI" if prec <= 0
n = prec + BigDecimal.double_fig
@@ -181,8 +215,15 @@ module BigMath
pi
end
+ # call-seq:
+ # E(numeric) -> BigDecimal
+ #
# Computes e (the base of natural logarithms) to the specified number of
- # digits of precision.
+ # digits of precision, +numeric+.
+ #
+ # BigMath::E(10).to_s
+ # #=> "0.271828182845904523536028752390026306410273E1"
+ #
def E(prec)
raise ArgumentError, "Zero or negative precision for E" if prec <= 0
n = prec + BigDecimal.double_fig