Ruby/Development/Math
Материал из Wiki.crossplatform.ru
Call to the class method sqrt from the Math module
puts Math.sqrt(16)
Convert polar coordinates to Cartesian coordinates
def cartesian(magnitude, angle) [magnitude*Math.cos(angle), magnitude*Math.sin(angle)] end
Convert the Cartesian point (x,y) to polar (magnitude, angle) coordinates
def polar(x,y) return Math.hypot(y,x), Math.atan2(y,x) end
do natural logarithms (base E or Euler) and base-10 logarithms.
Math.log(Math::E) # => 1.0 Math.log(1) # => 0.0 Math.log(0) # => -Infinity Math.log10(100.0) # => 2.0
Math functions from the Math module
Ruby methods ending in ! mean that the method makes in-place, or destructive, changes to an object, not to a copy of it. Method(s) Description Math.acos, Math.acos! Arc cosine Math.acosh, Math.acosh! Hyperbolic arc cosine Math.asin, Math.asin! Arc sine Math.asinh, Math.asinh Hyperbolic arc sine Math.atan, Math.atan!, Math.atan2, Math.atan2! Arc tangent; atan takes an x argument; atan2 takes an x and a y argument Math.atanh, Math.atanh! Hyperbolic arc tangent Math.cos, Math.cos! Cosine Math.cosh, Math.cosh Hyperbolic cosine Math.sin, Math.sin! Sine Math.erf Error function Match.erfc Complementary error function Math.exp, Math.exp! Base x of Euler Math.frexp Normalized fraction and exponent Math.hypot Hypotenuse Math.ldexp Floating-point value corresponding to a given mantissa and exponent Math.sinh, Math.sinh! Hyperbolic sine Math.sqrt, Math.sqrt! Square root Math.tan, Math.tan! Tangent Math.tanh, Math.tanh! Hyperbolic tangent
Random number
rand # => 0.964395196505186 rand # => 0.390523655919935 rand(100) # => 81 rand(100) # => 32
Random seeds
srand(0) # Known seed [rand(100),rand(100)] # => [44,47]: pseudorandom sequence srand(0) # Reset the seed to repeat the sequence [rand(100),rand(100)] # => [44,47]
Taking Logarithms
puts Math.log(1) # => 0.0 puts Math.log(Math::E) # => 1.0 puts Math.log(10) # => 2.30258509299405 puts Math::E ** Math.log(25) # => 25.0 puts Math.log10(1) # => 0.0 puts Math.log10(10) # => 1.0 puts Math.log10(10.1) # => 1.00432137378264 puts Math.log10(1000) # => 3.0 puts 10 ** Math.log10(25) # => 25.0
The Math.exp function returns Euler to the power of x.
Math.exp(1) # => 2.71828182845905 Math.exp(11) # => 59874.1417151978
The Math Object
puts(Math::PI) puts(Math::E) puts(Math.cos(Math::PI/3)) puts(Math.tan(Math::PI/4)) puts(Math.log(Math::E**2)) puts((1 + Math.sqrt(5))/2) # 3.14159265358979 # 2.71828182845905 # 0.5 # 1.0 # 2.0 # 1.61803398874989
