code review 8012043: math: modify a comment to the convention format.

src/pkg/math/tanh.go

 // Copyright 2009 The Go Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
 package math
 
 // The original C code, the long comment, and the constants
 // below were from http://netlib.sandia.gov/cephes/cmath/sin.c,
 // available from http://www.netlib.org/cephes/cmath.tgz.
 // The go code is a simplified version of the original C.
@@ skipping 47 matching lines @@
         -9.64399179425052238628E-1,
         -9.92877231001918586564E1,
         -1.61468768441708447952E3,
 }
 var tanhQ = [...]float64{
         1.12811678491632931402E2,
         2.23548839060100448583E3,
         4.84406305325125486048E3,
 }
 
-// Tanh computes the hyperbolic tangent of x.
+// Tanh returns the hyperbolic tangent of x.
 //
 // Special cases are:
 //      Tanh(±0) = ±0
 //      Tanh(±Inf) = ±1
 //      Tanh(NaN) = NaN
 func Tanh(x float64) float64 {
         const MAXLOG = 8.8029691931113054295988e+01 // log(2**127)
         z := Abs(x)
         switch {
         case z > 0.5*MAXLOG:
                 if x < 0 {
                         return -1
                 }
                 return 1
         case z >= 0.625:
                 s := Exp(2 * z)
                 z = 1 - 2/(s+1)
                 if x < 0 {
                         z = -z
                 }
         default:
                 if x == 0 {
                         return x
                 }
                 s := x * x
                 z = x + x*s*((tanhP[0]*s+tanhP[1])*s+tanhP[2])/(((s+tanhQ[0])*s+tanhQ[1])*s+tanhQ[2])
         }
         return z
 }