From b5afa049e942db44ea4bfe3433317c91783520cb Mon Sep 17 00:00:00 2001
From: Cabral <17774851+cabralski@users.noreply.github.com>
Date: Sat, 8 May 2021 08:32:18 -0300
Subject: [PATCH] math: sign function (#10014)

---
 vlib/math/const.v     |  2 +-
 vlib/math/math.v      | 23 ++++++++++++++++++++++
 vlib/math/math_test.v | 45 ++++++++++++++++++++++++++++++++++++++++++-
 3 files changed, 68 insertions(+), 2 deletions(-)

diff --git a/vlib/math/const.v b/vlib/math/const.v
index 7049680e4e..5a831a97c8 100644
--- a/vlib/math/const.v
+++ b/vlib/math/const.v
@@ -37,7 +37,7 @@ pub const (
 	min_i16 = -32768
 	max_i32 = 2147483647
 	min_i32 = -2147483648
-	// -9223372036854775808 is wrong because C compilers parse litteral values
+	// -9223372036854775808 is wrong because C compilers parse literal values
 	// without sign first, and 9223372036854775808 overflows i64, hence the
 	// consecutive subtraction by 1
 	min_i64 = i64(-9223372036854775807 - 1)
diff --git a/vlib/math/math.v b/vlib/math/math.v
index f7cb6f6d7e..f102f39257 100644
--- a/vlib/math/math.v
+++ b/vlib/math/math.v
@@ -31,11 +31,13 @@ pub fn aprox_cos(a f64) f64 {
 }
 
 // copysign returns a value with the magnitude of x and the sign of y
+[inline]
 pub fn copysign(x f64, y f64) f64 {
 	return f64_from_bits((f64_bits(x) & ~sign_mask) | (f64_bits(y) & sign_mask))
 }
 
 // degrees convert from degrees to radians.
+[inline]
 pub fn degrees(radians f64) f64 {
 	return radians * (180.0 / pi)
 }
@@ -59,6 +61,7 @@ pub fn digits(_n int, base int) []int {
 	return res
 }
 
+[inline]
 pub fn fabs(x f64) f64 {
 	if x < 0.0 {
 		return -x
@@ -99,6 +102,7 @@ pub fn lcm(a i64, b i64) i64 {
 }
 
 // max returns the maximum value of the two provided.
+[inline]
 pub fn max(a f64, b f64) f64 {
 	if a > b {
 		return a
@@ -107,6 +111,7 @@ pub fn max(a f64, b f64) f64 {
 }
 
 // min returns the minimum value of the two provided.
+[inline]
 pub fn min(a f64, b f64) f64 {
 	if a < b {
 		return a
@@ -114,12 +119,30 @@ pub fn min(a f64, b f64) f64 {
 	return b
 }
 
+// sign returns the corresponding sign -1.0, 1.0 of the provided number.
+// if n is not a number, its sign is nan too.
+[inline]
+pub fn sign(n f64) f64 {
+	if is_nan(n) {
+		return nan()
+	}
+	return copysign(1.0, n)
+}
+
+// signi returns the corresponding sign -1.0, 1.0 of the provided number.
+[inline]
+pub fn signi(n f64) int {
+	return int(copysign(1.0, n))
+}
+
 // radians convert from radians to degrees.
+[inline]
 pub fn radians(degrees f64) f64 {
 	return degrees * (pi / 180.0)
 }
 
 // signbit returns a value with the boolean representation of the sign for x
+[inline]
 pub fn signbit(x f64) bool {
 	return f64_bits(x) & sign_mask != 0
 }
diff --git a/vlib/math/math_test.v b/vlib/math/math_test.v
index 2aa0e5e640..b3dece0893 100644
--- a/vlib/math/math_test.v
+++ b/vlib/math/math_test.v
@@ -368,6 +368,49 @@ fn test_min() {
 	}
 }
 
+fn test_signi() {
+	assert signi(inf(-1)) == -1
+	assert signi(-72234878292.4586129) == -1
+	assert signi(-10) == -1
+	assert signi(-pi) == -1
+	assert signi(-1) == -1
+	assert signi(-0.000000000001) == -1
+	assert signi(-0.000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000001) == -1
+	assert signi(-0.0) == -1
+	//
+	assert signi(inf(1)) == 1
+	assert signi(72234878292.4586129) == 1
+	assert signi(10) == 1
+	assert signi(pi) == 1
+	assert signi(1) == 1
+	assert signi(0.000000000001) == 1
+	assert signi(0.000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000001) == 1
+	assert signi(0.0) == 1
+	assert signi(nan()) == 1
+}
+
+fn test_sign() {
+	assert sign(inf(-1)) == -1.0
+	assert sign(-72234878292.4586129) == -1.0
+	assert sign(-10) == -1.0
+	assert sign(-pi) == -1.0
+	assert sign(-1) == -1.0
+	assert sign(-0.000000000001) == -1.0
+	assert sign(-0.000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000001) == -1.0
+	assert sign(-0.0) == -1.0
+	//
+	assert sign(inf(1)) == 1.0
+	assert sign(72234878292.4586129) == 1
+	assert sign(10) == 1.0
+	assert sign(pi) == 1.0
+	assert sign(1) == 1.0
+	assert sign(0.000000000001) == 1.0
+	assert sign(0.000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000001) == 1.0
+	assert sign(0.0) == 1.0
+	assert is_nan(sign(nan()))
+	assert is_nan(sign(-nan()))
+}
+
 fn test_exp() {
 	for i := 0; i < math.vf_.len; i++ {
 		f := exp(math.vf_[i])
@@ -576,7 +619,7 @@ fn test_round() {
 		[f64(4503599627370495.5), 4503599627370496], /* 1 bit fraction, rounding to 0 bit fractian */
 		[f64(4503599627370497), 4503599627370497], /* large integer */
 	]
-	_ := vfround_even_sc_[0][0]    
+	_ := vfround_even_sc_[0][0]
 	for i := 0; i < vfround_sc_.len; i++ {
 		f := round(vfround_sc_[i][0])
 		assert alike(vfround_sc_[i][1], f)