1 files changed, 23 insertions, 0 deletions
diff --git a/lib/std/math/complex/sin.zig b/lib/std/math/complex/sin.zig
new file mode 100644
index 0000000000..9ddc3a7a80
--- /dev/null
+++ b/lib/std/math/complex/sin.zig
@@ -0,0 +1,23 @@
+const std = @import("../../std.zig");
+const testing = std.testing;
+const math = std.math;
+const cmath = math.complex;
+const Complex = cmath.Complex;
+
+/// Returns the sine of z.
+pub fn sin(z: var) Complex(@typeOf(z.re)) {
+    const T = @typeOf(z.re);
+    const p = Complex(T).new(-z.im, z.re);
+    const q = cmath.sinh(p);
+    return Complex(T).new(q.im, -q.re);
+}
+
+const epsilon = 0.0001;
+
+test "complex.csin" {
+    const a = Complex(f32).new(5, 3);
+    const c = sin(a);
+
+    testing.expect(math.approxEq(f32, c.re, -9.654126, epsilon));
+    testing.expect(math.approxEq(f32, c.im, 2.841692, epsilon));
+}