Method max_nmse_err

external/ggml/tests/test-backend-ops.cpp:1126–1128

    virtual ggml_tensor * build_graph(ggml_context * ctx) = 0;

    virtual double max_nmse_err() {
        return 1e-7;
    }

    virtual double max_nmse_err(ggml_backend_t backend) {
        ggml_backend_reg_t reg = ggml_backend_dev_backend_reg(ggml_backend_get_device(backend));