Robustified logsumexp

Author: fonnesbeck

pytensor/tensor/math.py

@@ -2753,8 +2753,8 @@ def logsumexp(x, axis=None, keepdims=False):
     tensor
 
     """
-
-    return log(sum(exp(x), axis=axis, keepdims=keepdims))
+    result = log(sum(exp(x - max(x, axis=axis, keepdims=True)), axis=axis, keepdims=keepdims))
+    return result + max(x, axis=axis, keepdims=keepdims)
 
 
 # Predefine all batched variations of Dot