234 lines
8.1 KiB
Plaintext
234 lines
8.1 KiB
Plaintext
/*
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* ******************************************************************************
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* *
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* *
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* * This program and the accompanying materials are made available under the
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* * terms of the Apache License, Version 2.0 which is available at
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* * https://www.apache.org/licenses/LICENSE-2.0.
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* *
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* * See the NOTICE file distributed with this work for additional
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* * information regarding copyright ownership.
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* * Unless required by applicable law or agreed to in writing, software
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* * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
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* * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
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* * License for the specific language governing permissions and limitations
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* * under the License.
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* *
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* * SPDX-License-Identifier: Apache-2.0
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* *****************************************************************************
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*/
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//
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// @author Yurii Shyrma (iuriish@yahoo.com)
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//
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#include <array/DataTypeUtils.h>
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#include <helpers/PointersManager.h>
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#include <ops/declarable/helpers/betaInc.h>
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#include <cmath>
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#include "execution/cuda/LaunchDims.h"
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namespace sd {
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namespace ops {
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namespace helpers {
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///////////////////////////////////////////////////////////////////
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// modified Lentz’s algorithm for continued fractions,
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// reference: Lentz, W.J. 1976, “Generating Bessel Functions in Mie Scattering Calculations Using Continued Fractions,”
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template <typename T>
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SD_DEVICE T continuedFractionCuda(const T a, const T b, const T x) {
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extern __shared__ unsigned char shmem[];
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T* coeffs = reinterpret_cast<T*>(shmem);
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const T min = DataTypeUtils::min<T>() / DataTypeUtils::eps<T>();
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const T aPlusb = a + b;
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T val, aPlus2i;
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T t2 = coeffs[1];
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T t1 = coeffs[0];
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if (math::sd_abs<T,T>(t1) < min) t1 = min;
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t1 = static_cast<T>(1) / t1;
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T result = t1;
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for (LongType i = 1; i <= maxIter; ++i) {
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const LongType i2 = 2 * i;
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aPlus2i = a + static_cast<T>(i2);
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// t1
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t1 = static_cast<T>(1) + coeffs[i2] * t1;
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if (math::sd_abs<T,T>(t1) < min) t1 = min;
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t1 = static_cast<T>(1) / t1;
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// t2
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t2 = static_cast<T>(1) + coeffs[i2] / t2;
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if (math::sd_abs<T,T>(t2) < min) t2 = min;
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// result
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result *= t2 * t1;
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// t1
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t1 = static_cast<T>(1) + coeffs[i2 + 1] * t1;
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if (math::sd_abs<T,T>(t1) < min) t1 = min;
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t1 = static_cast<T>(1) / t1;
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// t2
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t2 = static_cast<T>(1) + coeffs[i2 + 1] / t2;
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if (math::sd_abs<T,T>(t2) < min) t2 = min;
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// result
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val = t2 * t1;
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result *= val;
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// condition to stop loop
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if (math::sd_abs<T,T>(val - static_cast<T>(1)) <= DataTypeUtils::eps<T>()) return result;
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}
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return DataTypeUtils::infOrMax<T>(); // no convergence, more iterations is required, return infinity
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}
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///////////////////////////////////////////////////////////////////
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template <typename T>
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SD_KERNEL void betaIncForArrayCuda(const void* va, const LongType* aShapeInfo, const void* vb,
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const LongType* bShapeInfo, const void* vx, const LongType* xShapeInfo,
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void* vz, const LongType* zShapeInfo) {
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extern __shared__ unsigned char shmem[];
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T* sharedMem = reinterpret_cast<T*>(shmem);
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T* z = reinterpret_cast<T*>(vz);
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__shared__ LongType aLen, bLen, xLen, zLen, aOffset, bOffset, xOffset, zOffset;
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__shared__ int aRank, bRank, xRank, zRank;
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__shared__ const LongType *aShape, *bShape, *xShape, *zShape;
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__shared__ const LongType *aStride, *bStride, *xStride, *zStride;
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__shared__ T a, b, x;
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__shared__ bool symmCond;
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const LongType j = blockIdx.x; // one block per each element
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if (threadIdx.x == 0) {
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// Cache lengths
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aLen = shape::length(aShapeInfo);
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bLen = shape::length(bShapeInfo);
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xLen = shape::length(xShapeInfo);
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zLen = shape::length(zShapeInfo);
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// Cache ranks
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aRank = shape::rank(aShapeInfo);
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bRank = shape::rank(bShapeInfo);
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xRank = shape::rank(xShapeInfo);
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zRank = shape::rank(zShapeInfo);
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// Cache shapes
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aShape = shape::shapeOf(aShapeInfo);
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bShape = shape::shapeOf(bShapeInfo);
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xShape = shape::shapeOf(xShapeInfo);
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zShape = shape::shapeOf(zShapeInfo);
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// Cache strides
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aStride = shape::stride(aShapeInfo);
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bStride = shape::stride(bShapeInfo);
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xStride = shape::stride(xShapeInfo);
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zStride = shape::stride(zShapeInfo);
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LongType aCoords[SD_MAX_RANK];
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LongType bCoords[SD_MAX_RANK];
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LongType xCoords[SD_MAX_RANK];
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LongType zCoords[SD_MAX_RANK];
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INDEX2COORDS(j, aRank, aShape, aCoords);
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COORDS2INDEX(aRank, aStride, aCoords, aOffset);
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INDEX2COORDS(j, bRank, bShape, bCoords);
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COORDS2INDEX(bRank, bStride, bCoords, bOffset);
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INDEX2COORDS(j, xRank, xShape, xCoords);
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COORDS2INDEX(xRank, xStride, xCoords, xOffset);
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INDEX2COORDS(j, zRank, zShape, zCoords);
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COORDS2INDEX(zRank, zStride, zCoords, zOffset);
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if (aOffset >= aLen || bOffset >= bLen || xOffset >= xLen || zOffset >= zLen)
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return;
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a = *(reinterpret_cast<const T*>(va) + aOffset);
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b = *(reinterpret_cast<const T*>(vb) + bOffset);
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x = *(reinterpret_cast<const T*>(vx) + xOffset);
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symmCond = x > (a + T(1)) / (a + b + T(2));
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if (symmCond) { // swap a and b, x = 1 - x
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T temp = a;
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a = b;
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b = temp;
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x = T(1) - x;
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}
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}
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__syncthreads();
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// t^{n-1} * (1 - t)^{n-1} is symmetric function with respect to x = 0.5
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if (zOffset < zLen && a == b && x == T(0.5)) {
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z[zOffset] = T(0.5);
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return;
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}
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if (zOffset < zLen && (x == T(0) || x == T(1))) {
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if (symmCond) {
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z[zOffset] = T(1) - x;
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} else {
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z[zOffset] = x;
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}
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return;
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}
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// calculate two coefficients per thread
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if (threadIdx.x != 0) {
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const int i = threadIdx.x;
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const T aPlus2i = a + T(2) * T(i);
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sharedMem[2 * i] = T(i) * (b - T(i)) * x / ((aPlus2i - T(1)) * aPlus2i);
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sharedMem[2 * i + 1] = -(a + T(i)) * (a + b + T(i)) * x / ((aPlus2i + T(1)) * aPlus2i);
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}
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__syncthreads();
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if (threadIdx.x == 0) {
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const T gammaPart = static_cast<T>(lgamma(a)) + static_cast<T>(lgamma(b)) - static_cast<T>(lgamma(a + b));
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const T front = math::sd_exp<T, T>(math::sd_log<T, T>(x) * a + math::sd_log<T, T>(T(1) - x) * b - gammaPart);
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sharedMem[0] = T(1) - (a + b) * x / (a + T(1));
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sharedMem[1] = T(1);
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z[zOffset] = front * continuedFractionCuda(a, b, x) / a;
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if (symmCond) { // symmetry relation
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z[zOffset] = T(1) - z[zOffset];
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}
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}
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}
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///////////////////////////////////////////////////////////////////
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template <typename T>
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static void betaIncForArrayCudaLauncher(const int blocksPerGrid, const int threadsPerBlock, const int sharedMem,
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const cudaStream_t* stream, const void* va, const LongType* aShapeInfo,
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const void* vb, const LongType* bShapeInfo, const void* vx,
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const LongType* xShapeInfo, void* vz, const LongType* zShapeInfo) {
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betaIncForArrayCuda<T><<<blocksPerGrid, threadsPerBlock, sharedMem, *stream>>>(va, aShapeInfo, vb, bShapeInfo, vx,
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xShapeInfo, vz, zShapeInfo);
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sd::DebugHelper::checkGlobalErrorCode("betaInc failed");
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}
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///////////////////////////////////////////////////////////////////
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// overload betaInc for arrays, shapes of a, b and x must be the same !!!
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void betaInc(LaunchContext* context, NDArray& a, NDArray& b, NDArray& x, NDArray& output) {
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dim3 launchDims = getBetaInc(maxIter,output.lengthOf(),output.sizeOfT());
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const auto xType = x.dataType();
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PointersManager manager(context, "betaInc");
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NDArray::prepareSpecialUse({&output}, {&a, &b, &x});
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BUILD_SINGLE_SELECTOR(xType, betaIncForArrayCudaLauncher,
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(launchDims.y, launchDims.x, launchDims.z, context->getCudaStream(), a.specialBuffer(),
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a.specialShapeInfo(), b.specialBuffer(), b.specialShapeInfo(), x.specialBuffer(),
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x.specialShapeInfo(), output.specialBuffer(), output.specialShapeInfo()),
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SD_FLOAT_TYPES);
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NDArray::registerSpecialUse({&output}, {&a, &b, &x});
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manager.synchronize();
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}
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} // namespace helpers
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} // namespace ops
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} // namespace sd
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