Function test_regression

smallthinker/tests/test-opt.cpp:694–788

}

static std::pair<int, int> test_regression(ggml_backend_sched_t backend_sched, ggml_backend_t backend) {
    int ntest = 0;
    int npass = 0;

    // Test for simple regression with f(x) = a*x + b

    constexpr int64_t ndata_regression = 201;
    constexpr float a_true = 1.2f;
    constexpr float b_true = 3.4f;

    std::mt19937 gen(12345);
    std::normal_distribution<float> nd{0.0f, 0.1f};

    ggml_opt_dataset_t dataset = ggml_opt_dataset_init(
        GGML_TYPE_F32, GGML_TYPE_F32, 1, 1, ndata_regression, ndata_regression);

    float * data   = ggml_get_data_f32(ggml_opt_dataset_data(  dataset));
    float * labels = ggml_get_data_f32(ggml_opt_dataset_labels(dataset));

    constexpr float x_min = -100.0f;
    constexpr float x_max =  100.0f;

    for (int64_t idata = 0; idata < ndata_regression; ++idata) {
        const float x = x_min + (x_max - x_min) * idata/(ndata_regression-1);
        const float y = a_true*x + b_true + nd(gen);

        data[idata]   = x;
        labels[idata] = y;
    }

    struct ggml_context * ctx_static;
    struct ggml_context * ctx_compute;
    {
        struct ggml_init_params params = {
            /*.mem_size   =*/ 3*ggml_tensor_overhead(),
            /*.mem_buffer =*/ nullptr,
            /*.no_alloc   =*/ true,
        };
        ctx_static = ggml_init(params);
    }
    {
        struct ggml_init_params params = {
            /*.mem_size   =*/ GGML_DEFAULT_GRAPH_SIZE*ggml_tensor_overhead() + 3*ggml_graph_overhead(),
            /*.mem_buffer =*/ nullptr,
            /*.no_alloc   =*/ true,
        };
        ctx_compute = ggml_init(params);
    }

    // The first dimension is the dimension of the datapoints, the second dimension is the number of datapoints.
    struct ggml_tensor * x = ggml_new_tensor_2d(ctx_static, GGML_TYPE_F32, 1, ndata_regression);
    ggml_set_name(x, "x");

    struct ggml_tensor * a = ggml_new_tensor_1d(ctx_static, GGML_TYPE_F32, 1);
    ggml_set_name(a, "a");
    ggml_set_param(a);

    struct ggml_tensor * b = ggml_new_tensor_1d(ctx_static, GGML_TYPE_F32, 1);