module BigMath
Core BigMath methods for BigDecimal (log, exp) are defined here. Other methods (sin, cos, atan) are defined in ‘bigdecimal/math.rb’.
Provides mathematical functions.
Example:
require "bigdecimal/math" include BigMath a = BigDecimal((PI(49)/2).to_s) puts sin(a,100) # => 0.9999999999...9999999986e0
Public Instance Methods
Source
# File vendor/bundle/ruby/4.0.0/gems/bigdecimal-4.1.0/lib/bigdecimal/math.rb, line 923 def E(prec) prec = BigDecimal::Internal.coerce_validate_prec(prec, :E) exp(1, prec) end
Computes e (the base of natural logarithms) to the specified number of digits of precision, numeric.
BigMath.E(32).to_s #=> "0.27182818284590452353602874713527e1"
Source
# File vendor/bundle/ruby/4.0.0/gems/bigdecimal-4.1.0/lib/bigdecimal/math.rb, line 897 def PI(prec) # Gauss–Legendre algorithm prec = BigDecimal::Internal.coerce_validate_prec(prec, :PI) n = prec + BigDecimal::Internal::EXTRA_PREC a = BigDecimal(1) b = BigDecimal(0.5, 0).sqrt(n) s = BigDecimal(0.25, 0) t = 1 while a != b && (a - b).exponent > 1 - n c = (a - b).div(2, n) a, b = (a + b).div(2, n), (a * b).sqrt(n) s = s.sub(c * c * t, n) t *= 2 end (a * b).div(s, prec) end
Computes the value of pi to the specified number of digits of precision, numeric.
BigMath.PI(32).to_s #=> "0.31415926535897932384626433832795e1"
Source
# File vendor/bundle/ruby/4.0.0/gems/bigdecimal-4.1.0/lib/bigdecimal/math.rb, line 270 def acos(x, prec) prec = BigDecimal::Internal.coerce_validate_prec(prec, :acos) x = BigDecimal::Internal.coerce_to_bigdecimal(x, prec, :acos) raise Math::DomainError, "Out of domain argument for acos" if x < -1 || x > 1 return BigDecimal::Internal.nan_computation_result if x.nan? prec2 = prec + BigDecimal::Internal::EXTRA_PREC return (PI(prec2) / 2).sub(asin(x, prec2), prec) if x < 0 return PI(prec2).div(2, prec) if x.zero? sin = (1 - x**2).sqrt(prec2) atan(sin.div(x, prec2), prec) end
Computes the arccosine of decimal to the specified number of digits of precision, numeric.
If decimal is NaN, returns NaN.
BigMath.acos(BigDecimal('0.5'), 32).to_s #=> "0.10471975511965977461542144610932e1"
Source
# File vendor/bundle/ruby/4.0.0/gems/bigdecimal-4.1.0/lib/bigdecimal/math.rb, line 453 def acosh(x, prec) prec = BigDecimal::Internal.coerce_validate_prec(prec, :acosh) x = BigDecimal::Internal.coerce_to_bigdecimal(x, prec, :acosh) raise Math::DomainError, "Out of domain argument for acosh" if x < 1 return BigDecimal::Internal.infinity_computation_result if x.infinite? return BigDecimal::Internal.nan_computation_result if x.nan? log(x + sqrt(x**2 - 1, prec + BigDecimal::Internal::EXTRA_PREC), prec) end
Computes the inverse hyperbolic cosine of decimal to the specified number of digits of precision, numeric.
If decimal is NaN, returns NaN.
BigMath.acosh(BigDecimal('2'), 32).to_s #=> "0.1316957896924816708625046347308e1"
Source
# File vendor/bundle/ruby/4.0.0/gems/bigdecimal-4.1.0/lib/bigdecimal/math.rb, line 244 def asin(x, prec) prec = BigDecimal::Internal.coerce_validate_prec(prec, :asin) x = BigDecimal::Internal.coerce_to_bigdecimal(x, prec, :asin) raise Math::DomainError, "Out of domain argument for asin" if x < -1 || x > 1 return BigDecimal::Internal.nan_computation_result if x.nan? prec2 = prec + BigDecimal::Internal::EXTRA_PREC cos = (1 - x**2).sqrt(prec2) if cos.zero? PI(prec2).div(x > 0 ? 2 : -2, prec) else atan(x.div(cos, prec2), prec) end end
Computes the arcsine of decimal to the specified number of digits of precision, numeric.
If decimal is NaN, returns NaN.
BigMath.asin(BigDecimal('0.5'), 32).to_s #=> "0.52359877559829887307710723054658e0"
Source
# File vendor/bundle/ruby/4.0.0/gems/bigdecimal-4.1.0/lib/bigdecimal/math.rb, line 431 def asinh(x, prec) prec = BigDecimal::Internal.coerce_validate_prec(prec, :asinh) x = BigDecimal::Internal.coerce_to_bigdecimal(x, prec, :asinh) return BigDecimal::Internal.nan_computation_result if x.nan? return BigDecimal::Internal.infinity_computation_result * x.infinite? if x.infinite? return -asinh(-x, prec) if x < 0 sqrt_prec = prec + [-x.exponent, 0].max + BigDecimal::Internal::EXTRA_PREC log(x + sqrt(x**2 + 1, sqrt_prec), prec) end
Computes the inverse hyperbolic sine of decimal to the specified number of digits of precision, numeric.
If decimal is NaN, returns NaN.
BigMath.asinh(BigDecimal('1'), 32).to_s #=> "0.88137358701954302523260932497979e0"
Source
# File vendor/bundle/ruby/4.0.0/gems/bigdecimal-4.1.0/lib/bigdecimal/math.rb, line 295 def atan(x, prec) prec = BigDecimal::Internal.coerce_validate_prec(prec, :atan) x = BigDecimal::Internal.coerce_to_bigdecimal(x, prec, :atan) return BigDecimal::Internal.nan_computation_result if x.nan? n = prec + BigDecimal::Internal::EXTRA_PREC return PI(n).div(2 * x.infinite?, prec) if x.infinite? x = -x if neg = x < 0 x = BigDecimal(1).div(x, n) if inv = x < -1 || x > 1 # Solve tan(y) - x = 0 with Newton's method # Repeat: y -= (tan(y) - x) * cos(y)**2 y = BigDecimal(Math.atan(x.to_f), 0) BigDecimal::Internal.newton_loop(n) do |p| s = sin(y, p) c = (1 - s * s).sqrt(p) y = y.sub(c * (s.sub(c * x.mult(1, p), p)), p) end y = PI(n) / 2 - y if inv y.mult(neg ? -1 : 1, prec) end
Computes the arctangent of decimal to the specified number of digits of precision, numeric.
If decimal is NaN, returns NaN.
BigMath.atan(BigDecimal('-1'), 32).to_s #=> "-0.78539816339744830961566084581988e0"
Source
# File vendor/bundle/ruby/4.0.0/gems/bigdecimal-4.1.0/lib/bigdecimal/math.rb, line 326 def atan2(y, x, prec) prec = BigDecimal::Internal.coerce_validate_prec(prec, :atan2) x = BigDecimal::Internal.coerce_to_bigdecimal(x, prec, :atan2) y = BigDecimal::Internal.coerce_to_bigdecimal(y, prec, :atan2) return BigDecimal::Internal.nan_computation_result if x.nan? || y.nan? if x.infinite? || y.infinite? one = BigDecimal(1) zero = BigDecimal(0) x = x.infinite? ? (x > 0 ? one : -one) : zero y = y.infinite? ? (y > 0 ? one : -one) : y.sign * zero end return x.sign >= 0 ? BigDecimal(0) : y.sign * PI(prec) if y.zero? y = -y if neg = y < 0 xlarge = y.abs < x.abs prec2 = prec + BigDecimal::Internal::EXTRA_PREC if x > 0 v = xlarge ? atan(y.div(x, prec2), prec) : PI(prec2) / 2 - atan(x.div(y, prec2), prec2) else v = xlarge ? PI(prec2) - atan(-y.div(x, prec2), prec2) : PI(prec2) / 2 + atan(x.div(-y, prec2), prec2) end v.mult(neg ? -1 : 1, prec) end
Computes the arctangent of y and x to the specified number of digits of precision, numeric.
BigMath.atan2(BigDecimal('-1'), BigDecimal('1'), 32).to_s #=> "-0.78539816339744830961566084581988e0"
Source
# File vendor/bundle/ruby/4.0.0/gems/bigdecimal-4.1.0/lib/bigdecimal/math.rb, line 474 def atanh(x, prec) prec = BigDecimal::Internal.coerce_validate_prec(prec, :atanh) x = BigDecimal::Internal.coerce_to_bigdecimal(x, prec, :atanh) raise Math::DomainError, "Out of domain argument for atanh" if x < -1 || x > 1 return BigDecimal::Internal.nan_computation_result if x.nan? return BigDecimal::Internal.infinity_computation_result if x == 1 return -BigDecimal::Internal.infinity_computation_result if x == -1 prec2 = prec + BigDecimal::Internal::EXTRA_PREC (log(x + 1, prec2) - log(1 - x, prec2)).div(2, prec) end
Computes the inverse hyperbolic tangent of decimal to the specified number of digits of precision, numeric.
If decimal is NaN, returns NaN.
BigMath.atanh(BigDecimal('0.5'), 32).to_s #=> "0.54930614433405484569762261846126e0"
Source
# File vendor/bundle/ruby/4.0.0/gems/bigdecimal-4.1.0/lib/bigdecimal/math.rb, line 137 def cbrt(x, prec) prec = BigDecimal::Internal.coerce_validate_prec(prec, :cbrt) x = BigDecimal::Internal.coerce_to_bigdecimal(x, prec, :cbrt) return BigDecimal::Internal.nan_computation_result if x.nan? return BigDecimal::Internal.infinity_computation_result * x.infinite? if x.infinite? return BigDecimal(0) if x.zero? x = -x if neg = x < 0 ex = x.exponent / 3 x = x._decimal_shift(-3 * ex) y = BigDecimal(Math.cbrt(x.to_f), 0) BigDecimal::Internal.newton_loop(prec + BigDecimal::Internal::EXTRA_PREC) do |p| y = (2 * y + x.div(y, p).div(y, p)).div(3, p) end y._decimal_shift(ex).mult(neg ? -1 : 1, prec) end
Computes the cube root of decimal to the specified number of digits of precision, numeric.
BigMath.cbrt(BigDecimal('2'), 32).to_s #=> "0.12599210498948731647672106072782e1"
Source
# File vendor/bundle/ruby/4.0.0/gems/bigdecimal-4.1.0/lib/bigdecimal/math.rb, line 204 def cos(x, prec) prec = BigDecimal::Internal.coerce_validate_prec(prec, :cos) x = BigDecimal::Internal.coerce_to_bigdecimal(x, prec, :cos) return BigDecimal::Internal.nan_computation_result if x.infinite? || x.nan? n = prec + BigDecimal::Internal::EXTRA_PREC sign, x = _sin_periodic_reduction(x, n, add_half_pi: true) _sin_around_zero(x, n).mult(sign, prec) end
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(16), 32).to_s #=> "-0.99999999999999999999999999999997e0"
Source
# File vendor/bundle/ruby/4.0.0/gems/bigdecimal-4.1.0/lib/bigdecimal/math.rb, line 386 def cosh(x, prec) prec = BigDecimal::Internal.coerce_validate_prec(prec, :cosh) x = BigDecimal::Internal.coerce_to_bigdecimal(x, prec, :cosh) return BigDecimal::Internal.nan_computation_result if x.nan? return BigDecimal::Internal.infinity_computation_result if x.infinite? prec2 = prec + BigDecimal::Internal::EXTRA_PREC e = exp(x, prec2) (e + BigDecimal(1).div(e, prec2)).div(2, prec) end
Computes the hyperbolic cosine of decimal to the specified number of digits of precision, numeric.
If decimal is NaN, returns NaN.
BigMath.cosh(BigDecimal('1'), 32).to_s #=> "0.15430806348152437784779056207571e1"
Source
# File vendor/bundle/ruby/4.0.0/gems/bigdecimal-4.1.0/lib/bigdecimal/math.rb, line 598 def erf(x, prec) prec = BigDecimal::Internal.coerce_validate_prec(prec, :erf) x = BigDecimal::Internal.coerce_to_bigdecimal(x, prec, :erf) return BigDecimal::Internal.nan_computation_result if x.nan? return BigDecimal(x.infinite?) if x.infinite? return BigDecimal(0) if x == 0 return -erf(-x, prec) if x < 0 return BigDecimal(1) if x > 5000000000 # erf(5000000000) > 1 - 1e-10000000000000000000 if x > 8 xf = x.to_f log10_erfc = -xf ** 2 / Math.log(10) - Math.log10(xf * Math::PI ** 0.5) erfc_prec = [prec + log10_erfc.ceil, 1].max erfc = _erfc_asymptotic(x, erfc_prec) return BigDecimal(1).sub(erfc, prec) if erfc end prec2 = prec + BigDecimal::Internal::EXTRA_PREC x_smallprec = x.mult(1, Integer.sqrt(prec2) / 2) # Taylor series of x with small precision is fast erf1 = _erf_taylor(x_smallprec, BigDecimal(0), BigDecimal(0), prec2) # Taylor series converges quickly for small x _erf_taylor(x - x_smallprec, x_smallprec, erf1, prec2).mult(1, prec) end
Computes the error function of decimal to the specified number of digits of precision, numeric.
If decimal is NaN, returns NaN.
BigMath.erf(BigDecimal('1'), 32).to_s #=> "0.84270079294971486934122063508261e0"
Source
# File vendor/bundle/ruby/4.0.0/gems/bigdecimal-4.1.0/lib/bigdecimal/math.rb, line 634 def erfc(x, prec) prec = BigDecimal::Internal.coerce_validate_prec(prec, :erfc) x = BigDecimal::Internal.coerce_to_bigdecimal(x, prec, :erfc) return BigDecimal::Internal.nan_computation_result if x.nan? return BigDecimal(1 - x.infinite?) if x.infinite? return BigDecimal(1).sub(erf(x, prec + BigDecimal::Internal::EXTRA_PREC), prec) if x < 0.5 return BigDecimal(0) if x > 5000000000 # erfc(5000000000) < 1e-10000000000000000000 (underflow) if x >= 8 y = _erfc_asymptotic(x, prec) return y.mult(1, prec) if y end # erfc(x) = 1 - erf(x) < exp(-x**2)/x/sqrt(pi) # Precision of erf(x) needs about log10(exp(-x**2)/x/sqrt(pi)) extra digits log10 = 2.302585092994046 xf = x.to_f high_prec = prec + BigDecimal::Internal::EXTRA_PREC + ((xf**2 + Math.log(xf) + Math.log(Math::PI)/2) / log10).ceil BigDecimal(1).sub(erf(x, high_prec), prec) end
Computes the complementary error function of decimal to the specified number of digits of precision, numeric.
If decimal is NaN, returns NaN.
BigMath.erfc(BigDecimal('10'), 32).to_s #=> "0.20884875837625447570007862949578e-44"
Source
# File vendor/bundle/ruby/4.0.0/gems/bigdecimal-4.1.0/lib/bigdecimal.rb, line 349 def exp(x, prec) prec = BigDecimal::Internal.coerce_validate_prec(prec, :exp) x = BigDecimal::Internal.coerce_to_bigdecimal(x, prec, :exp) return BigDecimal::Internal.nan_computation_result if x.nan? return x.positive? ? BigDecimal::Internal.infinity_computation_result : BigDecimal(0) if x.infinite? return BigDecimal(1) if x.zero? # exp(x * 10**cnt) = exp(x)**(10**cnt) cnt = x < -1 || x > 1 ? x.exponent : 0 prec2 = prec + BigDecimal::Internal::EXTRA_PREC + cnt x = x._decimal_shift(-cnt) # Decimal form of bit-burst algorithm # Calculate exp(x.xxxxxxxxxxxxxxxx) as # exp(x.xx) * exp(0.00xx) * exp(0.0000xxxx) * exp(0.00000000xxxxxxxx) x = x.mult(1, prec2) n = 2 y = BigDecimal(1) BigDecimal.save_limit do BigDecimal.limit(0) while x != 0 do partial_x = x.truncate(n) x -= partial_x y = y.mult(_exp_binary_splitting(partial_x, prec2), prec2) n *= 2 end end # calculate exp(x * 10**cnt) from exp(x) # exp(x * 10**k) = exp(x * 10**(k - 1)) ** 10 cnt.times do y2 = y.mult(y, prec2) y5 = y2.mult(y2, prec2).mult(y, prec2) y = y5.mult(y5, prec2) end y.mult(1, prec) end
Computes the value of e (the base of natural logarithms) raised to the power of decimal, to the specified number of digits of precision.
If decimal is infinity, returns Infinity.
If decimal is NaN, returns NaN.
Source
# File vendor/bundle/ruby/4.0.0/gems/bigdecimal-4.1.0/lib/bigdecimal/math.rb, line 566 def expm1(x, prec) prec = BigDecimal::Internal.coerce_validate_prec(prec, :expm1) x = BigDecimal::Internal.coerce_to_bigdecimal(x, prec, :expm1) return BigDecimal(-1) if x.infinite? == -1 exp_prec = prec if x < -1 # log10(exp(x)) = x * log10(e) lg_e = 0.4342944819032518 exp_prec = prec + (lg_e * x).ceil + BigDecimal::Internal::EXTRA_PREC elsif x < 1 exp_prec = prec - x.exponent + BigDecimal::Internal::EXTRA_PREC else exp_prec = prec end return BigDecimal(-1) if exp_prec <= 0 exp(x, exp_prec).sub(1, prec) end
Computes exp(decimal) - 1 to the specified number of digits of precision, numeric.
BigMath.expm1(BigDecimal('0.1'), 32).to_s #=> "0.10517091807564762481170782649025e0"
Source
# File vendor/bundle/ruby/4.0.0/gems/bigdecimal-4.1.0/lib/bigdecimal/math.rb, line 866 def frexp(x) x = BigDecimal::Internal.coerce_to_bigdecimal(x, 0, :frexp) return [x, 0] unless x.finite? exponent = x.exponent [x._decimal_shift(-exponent), exponent] end
Decomposes x into a normalized fraction and an integral power of ten.
BigMath.frexp(BigDecimal(123.456)) #=> [0.123456e0, 3]
Source
# File vendor/bundle/ruby/4.0.0/gems/bigdecimal-4.1.0/lib/bigdecimal/math.rb, line 727 def gamma(x, prec) prec = BigDecimal::Internal.coerce_validate_prec(prec, :gamma) x = BigDecimal::Internal.coerce_to_bigdecimal(x, prec, :gamma) prec2 = prec + BigDecimal::Internal::EXTRA_PREC if x < 0.5 raise Math::DomainError, 'Numerical argument is out of domain - gamma' if x.frac.zero? # Euler's reflection formula: gamma(z) * gamma(1-z) = pi/sin(pi*z) pi = PI(prec2) sin = _sinpix(x, pi, prec2) return pi.div(gamma(1 - x, prec2).mult(sin, prec2), prec) elsif x.frac.zero? && x < 1000 * prec return _gamma_positive_integer(x, prec2).mult(1, prec) end a, sum = _gamma_spouge_sum_part(x, prec2) (x + (a - 1)).power(x - 0.5, prec2).mult(BigMath.exp(1 - x, prec2), prec2).mult(sum, prec) end
Computes the gamma function of decimal to the specified number of digits of precision, numeric.
BigMath.gamma(BigDecimal('0.5'), 32).to_s #=> "0.17724538509055160272981674833411e1"
Source
# File vendor/bundle/ruby/4.0.0/gems/bigdecimal-4.1.0/lib/bigdecimal/math.rb, line 163 def hypot(x, y, prec) prec = BigDecimal::Internal.coerce_validate_prec(prec, :hypot) x = BigDecimal::Internal.coerce_to_bigdecimal(x, prec, :hypot) y = BigDecimal::Internal.coerce_to_bigdecimal(y, prec, :hypot) return BigDecimal::Internal.nan_computation_result if x.nan? || y.nan? return BigDecimal::Internal.infinity_computation_result if x.infinite? || y.infinite? prec2 = prec + BigDecimal::Internal::EXTRA_PREC sqrt(x.mult(x, prec2) + y.mult(y, prec2), prec) end
Returns sqrt(x**2 + y**2) to the specified number of digits of precision, numeric.
BigMath.hypot(BigDecimal('1'), BigDecimal('2'), 32).to_s #=> "0.22360679774997896964091736687313e1"
Source
# File vendor/bundle/ruby/4.0.0/gems/bigdecimal-4.1.0/lib/bigdecimal/math.rb, line 883 def ldexp(x, exponent) x = BigDecimal::Internal.coerce_to_bigdecimal(x, 0, :ldexp) x.finite? ? x._decimal_shift(exponent) : x end
Inverse of frexp. Returns the value of fraction * 10**exponent.
BigMath.ldexp(BigDecimal("0.123456e0"), 3) #=> 0.123456e3
Source
# File vendor/bundle/ruby/4.0.0/gems/bigdecimal-4.1.0/lib/bigdecimal/math.rb, line 755 def lgamma(x, prec) prec = BigDecimal::Internal.coerce_validate_prec(prec, :lgamma) x = BigDecimal::Internal.coerce_to_bigdecimal(x, prec, :lgamma) prec2 = prec + BigDecimal::Internal::EXTRA_PREC if x < 0.5 return [BigDecimal::INFINITY, 1] if x.frac.zero? loop do # Euler's reflection formula: gamma(z) * gamma(1-z) = pi/sin(pi*z) pi = PI(prec2) sin = _sinpix(x, pi, prec2) log_gamma = BigMath.log(pi, prec2).sub(lgamma(1 - x, prec2).first + BigMath.log(sin.abs, prec2), prec) return [log_gamma, sin > 0 ? 1 : -1] if prec2 + log_gamma.exponent > prec + BigDecimal::Internal::EXTRA_PREC # Retry with higher precision if loss of significance is too large prec2 = prec2 * 3 / 2 end elsif x.frac.zero? && x < 1000 * prec log_gamma = BigMath.log(_gamma_positive_integer(x, prec2), prec) [log_gamma, 1] else # if x is close to 1 or 2, increase precision to reduce loss of significance diff1_exponent = (x - 1).exponent diff2_exponent = (x - 2).exponent extremely_near_one = diff1_exponent < -prec2 extremely_near_two = diff2_exponent < -prec2 if extremely_near_one || extremely_near_two # If x is extreamely close to base = 1 or 2, linear interpolation is accurate enough. # Taylor expansion at x = base is: (x - base) * digamma(base) + (x - base) ** 2 * trigamma(base) / 2 + ... # And we can ignore (x - base) ** 2 and higher order terms. base = extremely_near_one ? 1 : 2 d = BigDecimal(1)._decimal_shift(1 - prec2) log_gamma_d, sign = lgamma(base + d, prec2) return [log_gamma_d.mult(x - base, prec2).div(d, prec), sign] end prec2 += [-diff1_exponent, -diff2_exponent, 0].max a, sum = _gamma_spouge_sum_part(x, prec2) log_gamma = BigMath.log(sum, prec2).add((x - 0.5).mult(BigMath.log(x.add(a - 1, prec2), prec2), prec2) + 1 - x, prec) [log_gamma, 1] end end
Computes the natural logarithm of the absolute value of the gamma function of decimal to the specified number of digits of precision, numeric and its sign.
BigMath.lgamma(BigDecimal('0.5'), 32) #=> [0.57236494292470008707171367567653e0, 1]
Source
# File vendor/bundle/ruby/4.0.0/gems/bigdecimal-4.1.0/lib/bigdecimal.rb, line 296 def log(x, prec) prec = BigDecimal::Internal.coerce_validate_prec(prec, :log) raise Math::DomainError, 'Complex argument for BigMath.log' if Complex === x x = BigDecimal::Internal.coerce_to_bigdecimal(x, prec, :log) return BigDecimal::Internal.nan_computation_result if x.nan? raise Math::DomainError, 'Negative argument for log' if x < 0 return -BigDecimal::Internal.infinity_computation_result if x.zero? return BigDecimal::Internal.infinity_computation_result if x.infinite? return BigDecimal(0) if x == 1 prec2 = prec + BigDecimal::Internal::EXTRA_PREC # Reduce x to near 1 if x > 1.01 || x < 0.99 # log(x) = log(x/exp(logx_approx)) + logx_approx logx_approx = BigDecimal(BigDecimal::Internal.float_log(x), 0) x = x.div(exp(logx_approx, prec2), prec2) else logx_approx = BigDecimal(0) end # Solve exp(y) - x = 0 with Newton's method # Repeat: y -= (exp(y) - x) / exp(y) y = BigDecimal(BigDecimal::Internal.float_log(x), 0) exp_additional_prec = [-(x - 1).exponent, 0].max BigDecimal::Internal.newton_loop(prec2) do |p| expy = exp(y, p + exp_additional_prec) y = y.sub(expy.sub(x, p).div(expy, p), p) end y.add(logx_approx, prec) end
Computes the natural logarithm of decimal to the specified number of digits of precision, numeric.
If decimal is zero or negative, raises Math::DomainError.
If decimal is positive infinity, returns Infinity.
If decimal is NaN, returns NaN.
Source
# File vendor/bundle/ruby/4.0.0/gems/bigdecimal-4.1.0/lib/bigdecimal/math.rb, line 529 def log10(x, prec) prec = BigDecimal::Internal.coerce_validate_prec(prec, :log10) x = BigDecimal::Internal.coerce_to_bigdecimal(x, prec, :log10) return BigDecimal::Internal.nan_computation_result if x.nan? return BigDecimal::Internal.infinity_computation_result if x.infinite? == 1 prec2 = prec + BigDecimal::Internal::EXTRA_PREC * 3 / 2 v = log(x, prec2).div(log(BigDecimal(10), prec2), prec2) # Perform half-up rounding to calculate log10(10**n)==n correctly in every rounding mode v = v.round(prec + BigDecimal::Internal::EXTRA_PREC - (v.exponent < 0 ? v.exponent : 0), BigDecimal::ROUND_HALF_UP) v.mult(1, prec) end
Computes the base 10 logarithm of decimal to the specified number of digits of precision, numeric.
If decimal is zero or negative, raises Math::DomainError.
If decimal is positive infinity, returns Infinity.
If decimal is NaN, returns NaN.
BigMath.log10(BigDecimal('3'), 32).to_s #=> "0.47712125471966243729502790325512e0"
Source
# File vendor/bundle/ruby/4.0.0/gems/bigdecimal-4.1.0/lib/bigdecimal/math.rb, line 550 def log1p(x, prec) prec = BigDecimal::Internal.coerce_validate_prec(prec, :log1p) x = BigDecimal::Internal.coerce_to_bigdecimal(x, prec, :log1p) raise Math::DomainError, 'Out of domain argument for log1p' if x < -1 return log(x + 1, prec) end
Computes log(1 + decimal) to the specified number of digits of precision, numeric.
BigMath.log1p(BigDecimal('0.1'), 32).to_s #=> "0.95310179804324860043952123280765e-1"
Source
# File vendor/bundle/ruby/4.0.0/gems/bigdecimal-4.1.0/lib/bigdecimal/math.rb, line 501 def log2(x, prec) prec = BigDecimal::Internal.coerce_validate_prec(prec, :log2) x = BigDecimal::Internal.coerce_to_bigdecimal(x, prec, :log2) return BigDecimal::Internal.nan_computation_result if x.nan? return BigDecimal::Internal.infinity_computation_result if x.infinite? == 1 prec2 = prec + BigDecimal::Internal::EXTRA_PREC * 3 / 2 v = log(x, prec2).div(log(BigDecimal(2), prec2), prec2) # Perform half-up rounding to calculate log2(2**n)==n correctly in every rounding mode v = v.round(prec + BigDecimal::Internal::EXTRA_PREC - (v.exponent < 0 ? v.exponent : 0), BigDecimal::ROUND_HALF_UP) v.mult(1, prec) end
Computes the base 2 logarithm of decimal to the specified number of digits of precision, numeric.
If decimal is zero or negative, raises Math::DomainError.
If decimal is positive infinity, returns Infinity.
If decimal is NaN, returns NaN.
BigMath.log2(BigDecimal('3'), 32).to_s #=> "0.15849625007211561814537389439478e1"
Source
# File vendor/bundle/ruby/4.0.0/gems/bigdecimal-4.1.0/lib/bigdecimal/math.rb, line 184 def sin(x, prec) prec = BigDecimal::Internal.coerce_validate_prec(prec, :sin) x = BigDecimal::Internal.coerce_to_bigdecimal(x, prec, :sin) return BigDecimal::Internal.nan_computation_result if x.infinite? || x.nan? n = prec + BigDecimal::Internal::EXTRA_PREC sign, x = _sin_periodic_reduction(x, n) _sin_around_zero(x, n).mult(sign, prec) end
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, 32).to_s #=> "0.70710807985947359435812921837984e0"
Source
# File vendor/bundle/ruby/4.0.0/gems/bigdecimal-4.1.0/lib/bigdecimal/math.rb, line 363 def sinh(x, prec) prec = BigDecimal::Internal.coerce_validate_prec(prec, :sinh) x = BigDecimal::Internal.coerce_to_bigdecimal(x, prec, :sinh) return BigDecimal::Internal.nan_computation_result if x.nan? return BigDecimal::Internal.infinity_computation_result * x.infinite? if x.infinite? prec2 = prec + BigDecimal::Internal::EXTRA_PREC prec2 -= x.exponent if x.exponent < 0 e = exp(x, prec2) (e - BigDecimal(1).div(e, prec2)).div(2, prec) end
Computes the hyperbolic sine of decimal to the specified number of digits of precision, numeric.
If decimal is NaN, returns NaN.
BigMath.sinh(BigDecimal('1'), 32).to_s #=> "0.11752011936438014568823818505956e1"
Source
# File vendor/bundle/ruby/4.0.0/gems/bigdecimal-4.1.0/lib/bigdecimal/math.rb, line 64 def sqrt(x, prec) prec = BigDecimal::Internal.coerce_validate_prec(prec, :sqrt) x = BigDecimal::Internal.coerce_to_bigdecimal(x, prec, :sqrt) x.sqrt(prec) end
Computes the square root of decimal to the specified number of digits of precision, numeric.
BigMath.sqrt(BigDecimal('2'), 32).to_s #=> "0.14142135623730950488016887242097e1"
Source
# File vendor/bundle/ruby/4.0.0/gems/bigdecimal-4.1.0/lib/bigdecimal/math.rb, line 227 def tan(x, prec) prec = BigDecimal::Internal.coerce_validate_prec(prec, :tan) prec2 = prec + BigDecimal::Internal::EXTRA_PREC sin(x, prec2).div(cos(x, prec2), prec) end
Computes the tangent of decimal to the specified number of digits of precision, numeric.
If decimal is Infinity or NaN, returns NaN.
BigMath.tan(BigDecimal("0.0"), 4).to_s #=> "0.0" BigMath.tan(BigMath.PI(24) / 4, 32).to_s #=> "0.99999999999999999999999830836025e0"
Source
# File vendor/bundle/ruby/4.0.0/gems/bigdecimal-4.1.0/lib/bigdecimal/math.rb, line 408 def tanh(x, prec) prec = BigDecimal::Internal.coerce_validate_prec(prec, :tanh) x = BigDecimal::Internal.coerce_to_bigdecimal(x, prec, :tanh) return BigDecimal::Internal.nan_computation_result if x.nan? return BigDecimal(x.infinite?) if x.infinite? prec2 = prec + BigDecimal::Internal::EXTRA_PREC + [-x.exponent, 0].max e = exp(x, prec2) einv = BigDecimal(1).div(e, prec2) (e - einv).div(e + einv, prec) end
Computes the hyperbolic tangent of decimal to the specified number of digits of precision, numeric.
If decimal is NaN, returns NaN.
BigMath.tanh(BigDecimal('1'), 32).to_s #=> "0.76159415595576488811945828260479e0"