diff options
Diffstat (limited to 'lib/pure/rationals.nim')
| -rw-r--r-- | lib/pure/rationals.nim | 36 |
1 files changed, 36 insertions, 0 deletions
diff --git a/lib/pure/rationals.nim b/lib/pure/rationals.nim index 7907b4e6c..3946cf85b 100644 --- a/lib/pure/rationals.nim +++ b/lib/pure/rationals.nim @@ -241,6 +241,33 @@ proc abs*[T](x: Rational[T]): Rational[T] = result.num = abs x.num result.den = abs x.den +proc `div`*[T: SomeInteger](x, y: Rational[T]): T = + ## Computes the rational truncated division. + (x.num * y.den) div (y.num * x.den) + +proc `mod`*[T: SomeInteger](x, y: Rational[T]): Rational[T] = + ## Computes the rational modulo by truncated division (remainder). + ## This is same as ``x - (x div y) * y``. + result = ((x.num * y.den) mod (y.num * x.den)) // (x.den * y.den) + reduce(result) + +proc floorDiv*[T: SomeInteger](x, y: Rational[T]): T = + ## Computes the rational floor division. + ## + ## Floor division is conceptually defined as ``floor(x / y)``. + ## This is different from the ``div`` operator, which is defined + ## as ``trunc(x / y)``. That is, ``div`` rounds towards ``0`` and ``floorDiv`` + ## rounds down. + floorDiv(x.num * y.den, y.num * x.den) + +proc floorMod*[T: SomeInteger](x, y: Rational[T]): Rational[T] = + ## Computes the rational modulo by floor division (modulo). + ## + ## This is same as ``x - floorDiv(x, y) * y``. + ## This proc behaves the same as the ``%`` operator in python. + result = floorMod(x.num * y.den, y.num * x.den) // (x.den * y.den) + reduce(result) + proc hash*[T](x: Rational[T]): Hash = ## Computes hash for rational `x` # reduce first so that hash(x) == hash(y) for x == y @@ -339,3 +366,12 @@ when isMainModule: assert toRational(0.33) == 33 // 100 assert toRational(0.22) == 11 // 50 assert toRational(10.0) == 10 // 1 + + assert (1//1) div (3//10) == 3 + assert (-1//1) div (3//10) == -3 + assert (3//10) mod (1//1) == 3//10 + assert (-3//10) mod (1//1) == -3//10 + assert floorDiv(1//1, 3//10) == 3 + assert floorDiv(-1//1, 3//10) == -4 + assert floorMod(3//10, 1//1) == 3//10 + assert floorMod(-3//10, 1//1) == 7//10 |