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Diffstat (limited to 'ext/bigdecimal/lib/bigdecimal/math.rb')
| -rw-r--r-- | ext/bigdecimal/lib/bigdecimal/math.rb | 232 |
1 files changed, 0 insertions, 232 deletions
diff --git a/ext/bigdecimal/lib/bigdecimal/math.rb b/ext/bigdecimal/lib/bigdecimal/math.rb deleted file mode 100644 index 0b9d0648bb..0000000000 --- a/ext/bigdecimal/lib/bigdecimal/math.rb +++ /dev/null @@ -1,232 +0,0 @@ -# frozen_string_literal: false -require 'bigdecimal' - -# -#-- -# Contents: -# sqrt(x, prec) -# sin (x, prec) -# cos (x, prec) -# atan(x, prec) Note: |x|<1, x=0.9999 may not converge. -# PI (prec) -# E (prec) == exp(1.0,prec) -# -# where: -# x ... BigDecimal number to be computed. -# |x| must be small enough to get convergence. -# prec ... Number of digits to be obtained. -#++ -# -# Provides mathematical functions. -# -# Example: -# -# require "bigdecimal/math" -# -# include BigMath -# -# a = BigDecimal((PI(100)/2).to_s) -# puts sin(a,100) # => 0.99999999999999999999......e0 -# -module BigMath - module_function - - # call-seq: - # sqrt(decimal, numeric) -> BigDecimal - # - # Computes the square root of +decimal+ to the specified number of digits of - # precision, +numeric+. - # - # BigMath.sqrt(BigDecimal('2'), 16).to_s - # #=> "0.1414213562373095048801688724e1" - # - def sqrt(x, prec) - x.sqrt(prec) - end - - # 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" - # - def sin(x, prec) - raise ArgumentError, "Zero or negative precision for sin" if prec <= 0 - return BigDecimal("NaN") if x.infinite? || x.nan? - n = prec + BigDecimal.double_fig - one = BigDecimal("1") - two = BigDecimal("2") - x = -x if neg = x < 0 - if x > (twopi = two * BigMath.PI(prec)) - if x > 30 - x %= twopi - else - x -= twopi while x > twopi - end - end - x1 = x - x2 = x.mult(x,n) - sign = 1 - y = x - d = y - i = one - z = one - while d.nonzero? && ((m = n - (y.exponent - d.exponent).abs) > 0) - m = BigDecimal.double_fig if m < BigDecimal.double_fig - sign = -sign - x1 = x2.mult(x1,n) - i += two - z *= (i-one) * i - d = sign * x1.div(z,m) - y += d - end - neg ? -y : y - end - - # 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" - # - def cos(x, prec) - 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") - two = BigDecimal("2") - x = -x if x < 0 - if x > (twopi = two * BigMath.PI(prec)) - if x > 30 - x %= twopi - else - x -= twopi while x > twopi - end - end - x1 = one - x2 = x.mult(x,n) - sign = 1 - y = one - d = y - i = BigDecimal("0") - z = one - while d.nonzero? && ((m = n - (y.exponent - d.exponent).abs) > 0) - m = BigDecimal.double_fig if m < BigDecimal.double_fig - sign = -sign - x1 = x2.mult(x1,n) - i += two - z *= (i-one) * i - d = sign * x1.div(z,m) - y += d - end - y - end - - # 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('-1'), 16).to_s - # #=> "-0.785398163397448309615660845819878471907514682065e0" - # - def atan(x, prec) - raise ArgumentError, "Zero or negative precision for atan" if prec <= 0 - return BigDecimal("NaN") if x.nan? - pi = PI(prec) - x = -x if neg = x < 0 - return pi.div(neg ? -2 : 2, prec) if x.infinite? - return pi / (neg ? -4 : 4) if x.round(prec) == 1 - x = BigDecimal("1").div(x, prec) if inv = x > 1 - x = (-1 + sqrt(1 + x**2, prec))/x if dbl = x > 0.5 - n = prec + BigDecimal.double_fig - y = x - d = y - t = x - r = BigDecimal("3") - x2 = x.mult(x,n) - while d.nonzero? && ((m = n - (y.exponent - d.exponent).abs) > 0) - m = BigDecimal.double_fig if m < BigDecimal.double_fig - t = -t.mult(x2,n) - d = t.div(r,m) - y += d - r += 2 - end - y *= 2 if dbl - y = pi / 2 - y if inv - y = -y if neg - y - end - - # 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 precision for PI" if prec <= 0 - n = prec + BigDecimal.double_fig - zero = BigDecimal("0") - one = BigDecimal("1") - two = BigDecimal("2") - - m25 = BigDecimal("-0.04") - m57121 = BigDecimal("-57121") - - pi = zero - - d = one - k = one - t = BigDecimal("-80") - while d.nonzero? && ((m = n - (pi.exponent - d.exponent).abs) > 0) - m = BigDecimal.double_fig if m < BigDecimal.double_fig - t = t*m25 - d = t.div(k,m) - k = k+two - pi = pi + d - end - - d = one - k = one - t = BigDecimal("956") - while d.nonzero? && ((m = n - (pi.exponent - d.exponent).abs) > 0) - m = BigDecimal.double_fig if m < BigDecimal.double_fig - t = t.div(m57121,n) - d = t.div(k,m) - pi = pi + d - k = k+two - end - pi - end - - # call-seq: - # E(numeric) -> BigDecimal - # - # Computes e (the base of natural logarithms) to the specified number of - # 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 - BigMath.exp(1, prec) - end -end |