math,math/cmplx: fix linter issues

Change-Id: If061f1f120573cb109d97fa40806e160603cd593
Reviewed-on: https://go-review.googlesource.com/31871Reviewed-by: Rob Pike <r@golang.org>
Run-TryBot: Brad Fitzpatrick <bradfitz@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>

src/math/cmplx/tan.go

@@ -120,9 +120,9 @@ func tanSeries(z complex128) float64 {
 	rn := 0.0
 	d := 0.0
 	for {
-		rn += 1
+		rn++
 		f *= rn
-		rn += 1
+		rn++
 		f *= rn
 		x2 *= x
 		y2 *= y
@@ -130,9 +130,9 @@ func tanSeries(z complex128) float64 {
 		t /= f
 		d += t
 
-		rn += 1
+		rn++
 		f *= rn
-		rn += 1
+		rn++
 		f *= rn
 		x2 *= x
 		y2 *= y

src/math/expm1.go

@@ -229,7 +229,7 @@ func expm1(x float64) float64 {
 		}
 		t := Float64frombits(uint64(0x3ff-k) << 52) // 2**-k
 		y := x - (e + t)
-		y += 1
+		y++
 		y = Float64frombits(Float64bits(y) + uint64(k)<<52) // add k to y's exponent
 		return y
 	}

src/math/jn.go

@@ -174,7 +174,7 @@ func Jn(n int, x float64) float64 {
 			q1 := w*z - 1
 			k := 1
 			for q1 < 1e9 {
-				k += 1
+				k++
 				z += h
 				q0, q1 = q1, z*q1-q0
 			}

src/math/log1p.go

@@ -167,7 +167,7 @@ func log1p(x float64) float64 {
 		if iu < 0x0006a09e667f3bcd { // mantissa of Sqrt(2)
 			u = Float64frombits(iu | 0x3ff0000000000000) // normalize u
 		} else {
-			k += 1
+			k++
 			u = Float64frombits(iu | 0x3fe0000000000000) // normalize u/2
 			iu = (0x0010000000000000 - iu) >> 2
 		}
@@ -179,10 +179,9 @@ func log1p(x float64) float64 {
 		if f == 0 {
 			if k == 0 {
 				return 0
-			} else {
-				c += float64(k) * Ln2Lo
-				return float64(k)*Ln2Hi + c
 			}
+			c += float64(k) * Ln2Lo
+			return float64(k)*Ln2Hi + c
 		}
 		R = hfsq * (1.0 - 0.66666666666666666*f) // avoid division
 		if k == 0 {

src/math/sin.go

@@ -140,8 +140,8 @@ func cos(x float64) float64 {
 
 	// map zeros to origin
 	if j&1 == 1 {
-		j += 1
-		y += 1
+		j++
+		y++
 	}
 	j &= 7 // octant modulo 2Pi radians (360 degrees)
 	if j > 3 {
@@ -200,8 +200,8 @@ func sin(x float64) float64 {
 
 	// map zeros to origin
 	if j&1 == 1 {
-		j += 1
-		y += 1
+		j++
+		y++
 	}
 	j &= 7 // octant modulo 2Pi radians (360 degrees)
 	// reflect in x axis

src/math/sincos.go

@@ -40,8 +40,8 @@ func sincos(x float64) (sin, cos float64) {
 	y := float64(j)      // integer part of x/(Pi/4), as float
 
 	if j&1 == 1 { // map zeros to origin
-		j += 1
-		y += 1
+		j++
+		y++
 	}
 	j &= 7     // octant modulo 2Pi radians (360 degrees)
 	if j > 3 { // reflect in x axis

src/math/tan.go

@@ -108,8 +108,8 @@ func tan(x float64) float64 {
 
 	/* map zeros and singularities to origin */
 	if j&1 == 1 {
-		j += 1
-		y += 1
+		j++
+		y++
 	}
 
 	z := ((x - y*PI4A) - y*PI4B) - y*PI4C