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-rw-r--r--src/pkg/math/atan.go62
1 files changed, 0 insertions, 62 deletions
diff --git a/src/pkg/math/atan.go b/src/pkg/math/atan.go
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--- a/src/pkg/math/atan.go
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-// 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
-
-/*
- Floating-point arctangent.
-
- Atan returns the value of the arctangent of its
- argument in the range [-pi/2,pi/2].
- There are no error returns.
- Coefficients are #5077 from Hart & Cheney. (19.56D)
-*/
-
-// xatan evaluates a series valid in the
-// range [-0.414...,+0.414...]. (tan(pi/8))
-func xatan(arg float64) float64 {
- const (
- P4 = .161536412982230228262e2
- P3 = .26842548195503973794141e3
- P2 = .11530293515404850115428136e4
- P1 = .178040631643319697105464587e4
- P0 = .89678597403663861959987488e3
- Q4 = .5895697050844462222791e2
- Q3 = .536265374031215315104235e3
- Q2 = .16667838148816337184521798e4
- Q1 = .207933497444540981287275926e4
- Q0 = .89678597403663861962481162e3
- )
- sq := arg * arg
- value := ((((P4*sq+P3)*sq+P2)*sq+P1)*sq + P0)
- value = value / (((((sq+Q4)*sq+Q3)*sq+Q2)*sq+Q1)*sq + Q0)
- return value * arg
-}
-
-// satan reduces its argument (known to be positive)
-// to the range [0,0.414...] and calls xatan.
-func satan(arg float64) float64 {
- if arg < Sqrt2-1 {
- return xatan(arg)
- }
- if arg > Sqrt2+1 {
- return Pi/2 - xatan(1/arg)
- }
- return Pi/4 + xatan((arg-1)/(arg+1))
-}
-
-// Atan returns the arctangent of x.
-//
-// Special cases are:
-// Atan(±0) = ±0
-// Atan(±Inf) = ±Pi/2
-func Atan(x float64) float64 {
- if x == 0 {
- return x
- }
- if x > 0 {
- return satan(x)
- }
- return -satan(-x)
-}