message: Explicitly defining PI to fix windows build.
diff: @@ -17,6 +17,7 @@ limitations under the License.
  #define TENSORFLOW_CORE_KERNELS_SAMPLING_KERNELS_H_
  #include <cmath>
  +
  #include "tensorflow/core/lib/core/stringpiece.h"
  namespace tensorflow {
  @@ -68,14 +69,15 @@ struct LanczosKernelFunc {
  // Pass 1 for Lanczos1 kernel, 3 for Lanczos3 etc.
  explicit LanczosKernelFunc(float _radius) : radius(_radius) {}
  float operator()(float x) const {
  + constexpr float kPI = 3.14159265359;
  x = std::abs(x);
  if (x > radius) return 0.0;
  // Need to special case the limit case of sin(x) / x when x is zero.
  if (x <= 1e-3) {
  return 1.0;
  }
  - return radius * std::sin(M_PI * x) * std::sin(M_PI * x / radius) /
  - (M_PI * M_PI * x * x);
  + return radius * std::sin(kPI * x) * std::sin(kPI * x / radius) /
  + (kPI * kPI * x * x);
  }
  float Radius() const { return radius; }
  const float radius;
  