From a747e74440dd0ad4846b8f7c59492bfa3394bcc2 Mon Sep 17 00:00:00 2001
From: ThomasHeede <145970483+ThomasHeede@users.noreply.github.com>
Date: Wed, 15 Oct 2025 11:51:05 +0200
Subject: [PATCH] Fix _log_beta_1 function for non-integer alphas

The function __log_beta_1_ cannot handle the argument _is_sparse=True_ due to incorrect data type of instantiating _result = torch.zeros_like(value)_. I propose to add that the dtype should be the same as _alpha_; thus,  _result = torch.zeros_like(value, dtype=alpha.dtype)_.

The problem arises when:
_result[mask] = (torch.lgamma(1 + value) + torch.lgamma(alpha) - torch.lgamma(value + alpha))_,
as result[mask].dtype >> torch.int64 and (torch.lgamma(1 + value) + torch.lgamma(alpha) - torch.lgamma(value + alpha)).dtype >> torch.float32
---
 pyro/distributions/conjugate.py | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/pyro/distributions/conjugate.py b/pyro/distributions/conjugate.py
index ffb37f3148..ce5cc59574 100644
--- a/pyro/distributions/conjugate.py
+++ b/pyro/distributions/conjugate.py
@@ -18,7 +18,7 @@ def _log_beta_1(alpha, value, is_sparse):
     if is_sparse:
         mask = value != 0
         value, alpha, mask = torch.broadcast_tensors(value, alpha, mask)
-        result = torch.zeros_like(value)
+        result = torch.zeros_like(value, dtype=alpha.dtype)
         value = value[mask]
         alpha = alpha[mask]
         result[mask] = (