The patch looks better than mine, I think we can merge this patch into master. Any comments?
> --------
>
> Compare with tgamma instead of tgammaf for better accuracy.
> Include negative inputs, and handle the resulting denormals.
> Print maximum error found.
>
> Signed-off-by: Rebecca Palmer <rebecca_palmer at zoho.com>
>
> diff --git a/utests/builtin_tgamma.cpp b/utests/builtin_tgamma.cpp index
> 47cc5f4..b7db69b 100644
> --- a/utests/builtin_tgamma.cpp
> +++ b/utests/builtin_tgamma.cpp
> @@ -20,10 +20,15 @@ void builtin_tgamma(void)
> if (env_strict == NULL || strcmp(env_strict, "0") == 0)
> ULPSIZE_FACTOR = 10000.;
>
> - for (int j = 0; j < 1024; j ++) {
> + cl_device_fp_config fp_config;
> + clGetDeviceInfo(device, CL_DEVICE_SINGLE_FP_CONFIG,
> + sizeof(cl_device_fp_config), &fp_config, 0); bool denormals_supported
> + = fp_config & CL_FP_DENORM; float max_ulp = 0, max_ulp_at = 0;
> +
> + for (int j = 0; j < 128; j ++) {
> OCL_MAP_BUFFER(0);
> for (int i = 0; i < n; ++i) {
> - src[i] = ((float*)buf_data[0])[i] = (j*n+i+1) * 0.001f;
> + src[i] = ((float*)buf_data[0])[i] = j - 64 + i*0.001f;
> }
> OCL_UNMAP_BUFFER(0);
>
> @@ -32,7 +37,14 @@ void builtin_tgamma(void)
> OCL_MAP_BUFFER(1);
> float *dst = (float*)buf_data[1];
> for (int i = 0; i < n; ++i) {
> - float cpu = tgammaf(src[i]);
> + float cpu = tgamma(src[i]);
> + if (!denormals_supported && std::fpclassify(cpu)==FP_SUBNORMAL
> && dst[i]==0) {
> + cpu = 0;
> + }
> + if (fabsf(cpu - dst[i]) > cl_FLT_ULP(cpu) * max_ulp) {
> + max_ulp = fabsf(cpu - dst[i]) / cl_FLT_ULP(cpu);
> + max_ulp_at = src[i];
> + }
> if (isinf(cpu)) {
> OCL_ASSERT(isinf(dst[i]));
> } else if (fabsf(cpu - dst[i]) >= cl_FLT_ULP(cpu) * ULPSIZE_FACTOR)
> { @@ -42,6 +54,7 @@ void builtin_tgamma(void)
> }
> OCL_UNMAP_BUFFER(1);
> }
> + printf("max error=%f ulp at x=%f ", max_ulp, max_ulp_at);
> }
>
> MAKE_UTEST_FROM_FUNCTION(builtin_tgamma);
>
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