chore: import upstream snapshot with attribution

paddle/phi/kernels/cpu/logspace_kernel.cc

@@ -0,0 +1,78 @@
+// Copyright (c) 2022 PaddlePaddle Authors. All Rights Reserved.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+#include "paddle/phi/kernels/logspace_kernel.h"
+
+#include <cmath>
+
+#include "paddle/phi/backends/cpu/cpu_context.h"
+#include "paddle/phi/core/kernel_registry.h"
+#include "paddle/phi/kernels/funcs/data_type_transform.h"
+
+namespace phi {
+
+template <typename T, typename Context>
+void LogspaceKernel(const Context& dev_ctx,
+                    const DenseTensor& start,
+                    const DenseTensor& stop,
+                    const DenseTensor& number,
+                    const DenseTensor& base,
+                    DataType dtype,
+                    DenseTensor* out) {
+  int32_t num = number.data<int32_t>()[0];
+  auto start_t = funcs::TransDataType(dev_ctx, start, dtype);
+  auto stop_t = funcs::TransDataType(dev_ctx, stop, dtype);
+  auto base_t = funcs::TransDataType(dev_ctx, base, dtype);
+
+  T start_data = start_t.template data<T>()[0];
+  T stop_data = stop_t.template data<T>()[0];
+  T base_data = base_t.template data<T>()[0];
+  PADDLE_ENFORCE_GT(
+      num,
+      0,
+      common::errors::InvalidArgument("The num of logspace op should be larger "
+                                      "than 0, but received num is %d",
+                                      num));
+
+  out->Resize({num});
+  T* out_data = dev_ctx.template Alloc<T>(out);
+
+  if (num > 1) {
+    // step should be of double type for all types
+    double step = (static_cast<double>(stop_data - start_data)) / (num - 1);
+    int half_num = num / 2;
+    for (int i = 0; i < num; ++i) {
+      if (i < half_num) {
+        out_data[i] =
+            static_cast<T>(std::pow(base_data, start_data + step * i));
+      } else {
+        out_data[i] = static_cast<T>(
+            std::pow(base_data, stop_data - step * (num - i - 1)));
+      }
+    }
+  } else {
+    out_data[0] = static_cast<T>(std::pow(base_data, start_data));
+  }
+}
+
+}  // namespace phi
+
+PD_REGISTER_KERNEL(logspace,
+                   CPU,
+                   ALL_LAYOUT,
+                   phi::LogspaceKernel,
+                   float,
+                   int32_t,
+                   int64_t,
+                   double) {}