use fp32 for testing, add more complex ops (#2322)

mlx/backend/cuda/device/unary_ops.cuh

@@ -27,6 +27,8 @@ struct ArcCos {
   __device__ T operator()(T x) {
     return acos(x);
   }
+
+  __device__ cuComplex operator()(cuComplex x);
 };
 
 struct ArcCosh {
@@ -41,6 +43,8 @@ struct ArcSin {
   __device__ T operator()(T x) {
     return asin(x);
   }
+
+  __device__ cuComplex operator()(cuComplex x);
 };
 
 struct ArcSinh {
@@ -55,6 +59,8 @@ struct ArcTan {
   __device__ T operator()(T x) {
     return atan(x);
   }
+
+  __device__ cuComplex operator()(cuComplex x);
 };
 
 struct ArcTanh {
@@ -261,13 +267,6 @@ struct Round {
   }
 };
 
-struct Rsqrt {
-  template <typename T>
-  __device__ T operator()(T x) {
-    return rsqrt(x);
-  }
-};
-
 struct Sigmoid {
   template <typename T>
   __device__ T operator()(T x) {
@@ -333,6 +332,29 @@ struct Sqrt {
   __device__ T operator()(T x) {
     return sqrt(x);
   }
+
+  __device__ cuComplex operator()(cuComplex x) {
+    auto xr = cuCrealf(x);
+    auto xi = cuCimagf(x);
+    if (xr == 0.0f && xi == 0.0f) {
+      return {0.0f, 0.0f};
+    }
+    auto r = cuCrealf(Abs{}(x));
+    auto a = sqrt((r + xr) / 2.0f);
+    auto b_abs = sqrt((r - xr) / 2.0f);
+    auto b = copysign(b_abs, xi);
+    return {a, b};
+  }
+};
+
+struct Rsqrt {
+  template <typename T>
+  __device__ T operator()(T x) {
+    return rsqrt(x);
+  }
+  __device__ cuComplex operator()(cuComplex x) {
+    return 1.0f / Sqrt{}(x);
+  }
 };
 
 struct Tan {
@@ -365,4 +387,22 @@ struct Tanh {
   }
 };
 
+__device__ cuComplex ArcCos::operator()(cuComplex x) {
+  auto i = cuComplex{0.0, 1.0};
+  auto y = Log{}(x + i * Sqrt{}(1.0 - x * x));
+  return {cuCimagf(y), -cuCrealf(y)};
+};
+
+__device__ cuComplex ArcSin::operator()(cuComplex x) {
+  auto i = cuComplex{0.0f, 1.0f};
+  auto y = Log{}(i * x + Sqrt{}(1.0f - x * x));
+  return {cuCimagf(y), -cuCrealf(y)};
+};
+
+__device__ cuComplex ArcTan::operator()(cuComplex x) {
+  auto i = cuComplex{0.0f, 1.0f};
+  auto ix = i * x;
+  return (1.0f / cuComplex{0.0f, 2.0f}) * Log{}((1.0f + ix) / (1.0f - ix));
+};
+
 } // namespace mlx::core::cu