Merge pull request #7950 from Paalon/math-log

Add log for base b of x
This commit is contained in:
Andreas Rumpf
2018-06-14 14:02:57 +02:00
committed by GitHub

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@@ -147,6 +147,18 @@ when not defined(JS): # C
proc ln*(x: float32): float32 {.importc: "logf", header: "<math.h>".}
proc ln*(x: float64): float64 {.importc: "log", header: "<math.h>".}
## Computes the natural log of `x`
else: # JS
proc sqrt*(x: float32): float32 {.importc: "Math.sqrt", nodecl.}
proc sqrt*(x: float64): float64 {.importc: "Math.sqrt", nodecl.}
proc ln*(x: float32): float32 {.importc: "Math.log", nodecl.}
proc ln*(x: float64): float64 {.importc: "Math.log", nodecl.}
proc log*[T: SomeFloat](x, base: T): T =
## Computes the logarithm ``base`` of ``x``
ln(x) / ln(base)
when not defined(JS): # C
proc log10*(x: float32): float32 {.importc: "log10f", header: "<math.h>".}
proc log10*(x: float64): float64 {.importc: "log10", header: "<math.h>".}
## Computes the common logarithm (base 10) of `x`
@@ -204,11 +216,6 @@ when not defined(JS): # C
## Computes the inverse hyperbolic tangent of `x`
else: # JS
proc sqrt*(x: float32): float32 {.importc: "Math.sqrt", nodecl.}
proc sqrt*(x: float64): float64 {.importc: "Math.sqrt", nodecl.}
proc ln*(x: float32): float32 {.importc: "Math.log", nodecl.}
proc ln*(x: float64): float64 {.importc: "Math.log", nodecl.}
proc log10*(x: float32): float32 {.importc: "Math.log10", nodecl.}
proc log10*(x: float64): float64 {.importc: "Math.log10", nodecl.}
proc log2*(x: float32): float32 {.importc: "Math.log2", nodecl.}
@@ -682,3 +689,6 @@ when isMainModule:
doAssert floorMod(8.0, -3.0) ==~ -1.0
doAssert floorMod(-8.5, 3.0) ==~ 0.5
block: # log
doAssert log(4.0, 3.0) == ln(4.0) / ln(3.0)