cuda.loss.logisticloss.LogisticLossKernel.cu Maven / Gradle / Ivy

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Komputation is a neural network framework for the JVM written in the Kotlin programming language.

There is a newer version: 0.12.5

#include "reduction/ProductReduction.cuh"

/*
    step 1: 0.8
    step 2: 0.9
    -logf(0.8) + -logf(0.9) = -logf(0.8 * 0.9)
*/

__inline__ __device__ float probability(float prediction, float target) {

    return target * prediction + (1.0 - target) * (1.0 - prediction);

}

__global__ void logisticLossKernel (int batchSize, int numberColumns, int numberIterations, float* predictions, float* targets, float* results)
{

    extern __shared__ float sharedData[];

    int indexInstance = blockIdx.x;

    if(indexInstance < batchSize) {

        float thisValue = 1.0;

        int startInstance = indexInstance * numberColumns;
        int startNextInstance = startInstance + numberColumns;

        int startWithinBatch = startInstance + threadIdx.x * numberIterations;

        for(int indexEntry = startWithinBatch; indexEntry < startWithinBatch + numberIterations; indexEntry++) {

            thisValue *= indexEntry < startNextInstance ? probability(predictions[indexEntry], targets[indexEntry]) : 1.0;

        }

        int warpId = threadIdx.x / warpSize;
        int laneId = threadIdx.x % warpSize;

        reduceToProduct(thisValue, warpId, laneId, sharedData);

        if(threadIdx.x == 0) {

            results[indexInstance] = -logf(sharedData[0]);

        }

    }
    else {

        if(threadIdx.x == 0) {

            results[indexInstance] = 0.0;

        }

    }

}