1 files changed, 113 insertions, 0 deletions
diff --git a/v_windows/v/vlib/math/tan.v b/v_windows/v/vlib/math/tan.v
new file mode 100644
index 0000000..b37287f
--- /dev/null
+++ b/v_windows/v/vlib/math/tan.v
@@ -0,0 +1,113 @@
+module math
+
+const (
+	tan_p      = [
+		-1.30936939181383777646e+4,
+		1.15351664838587416140e+6,
+		-1.79565251976484877988e+7,
+	]
+	tan_q      = [
+		1.00000000000000000000e+0,
+		1.36812963470692954678e+4,
+		-1.32089234440210967447e+6,
+		2.50083801823357915839e+7,
+		-5.38695755929454629881e+7,
+	]
+	tan_dp1    = 7.853981554508209228515625e-1
+	tan_dp2    = 7.94662735614792836714e-9
+	tan_dp3    = 3.06161699786838294307e-17
+	tan_lossth = 1.073741824e+9
+)
+
+// tan calculates tangent of a number
+pub fn tan(a f64) f64 {
+	mut x := a
+	if x == 0.0 || is_nan(x) {
+		return x
+	}
+	if is_inf(x, 0) {
+		return nan()
+	}
+	mut sign := 1 // make argument positive but save the sign
+	if x < 0 {
+		x = -x
+		sign = -1
+	}
+	if x > math.tan_lossth {
+		return 0.0
+	}
+	// compute x mod pi_4
+	mut y := floor(x * 4.0 / pi) // strip high bits of integer part
+	mut z := ldexp(y, -3)
+	z = floor(z) // integer part of y/8
+	z = y - ldexp(z, 3) // y - 16 * (y/16) // integer and fractional part modulo one octant
+	mut octant := int(z) // map zeros and singularities to origin
+	if (octant & 1) == 1 {
+		octant++
+		y += 1.0
+	}
+	z = ((x - y * math.tan_dp1) - y * math.tan_dp2) - y * math.tan_dp3
+	zz := z * z
+	if zz > 1.0e-14 {
+		y = z + z * (zz * (((math.tan_p[0] * zz) + math.tan_p[1]) * zz + math.tan_p[2]) / ((((zz +
+			math.tan_q[1]) * zz + math.tan_q[2]) * zz + math.tan_q[3]) * zz + math.tan_q[4]))
+	} else {
+		y = z
+	}
+	if (octant & 2) == 2 {
+		y = -1.0 / y
+	}
+	if sign < 0 {
+		y = -y
+	}
+	return y
+}
+
+// tanf calculates tangent. (float32)
+[inline]
+pub fn tanf(a f32) f32 {
+	return f32(tan(a))
+}
+
+// tan calculates cotangent of a number
+pub fn cot(a f64) f64 {
+	mut x := a
+	if x == 0.0 {
+		return inf(1)
+	}
+	mut sign := 1 // make argument positive but save the sign
+	if x < 0 {
+		x = -x
+		sign = -1
+	}
+	if x > math.tan_lossth {
+		return 0.0
+	}
+	// compute x mod pi_4
+	mut y := floor(x * 4.0 / pi) // strip high bits of integer part
+	mut z := ldexp(y, -3)
+	z = floor(z) // integer part of y/8
+	z = y - ldexp(z, 3) // y - 16 * (y/16) // integer and fractional part modulo one octant
+	mut octant := int(z) // map zeros and singularities to origin
+	if (octant & 1) == 1 {
+		octant++
+		y += 1.0
+	}
+	z = ((x - y * math.tan_dp1) - y * math.tan_dp2) - y * math.tan_dp3
+	zz := z * z
+	if zz > 1.0e-14 {
+		y = z + z * (zz * (((math.tan_p[0] * zz) + math.tan_p[1]) * zz + math.tan_p[2]) / ((((zz +
+			math.tan_q[1]) * zz + math.tan_q[2]) * zz + math.tan_q[3]) * zz + math.tan_q[4]))
+	} else {
+		y = z
+	}
+	if (octant & 2) == 2 {
+		y = -y
+	} else {
+		y = 1.0 / y
+	}
+	if sign < 0 {
+		y = -y
+	}
+	return y
+}