I would expect sympy.powsimp to combine factors exp(subexprA)*exp(subexprB) into exp(subexprA+subexprB) in all cases. However, it fails to do so whenever either subexprA or subexprB are UnevaluatedExprs.

For example, when I try this:

import sympy

expr1 = sympy.sympify("exp(T)")
expr2 = sympy.UnevaluatedExpr(sympy.sympify("T"))
old_expr = expr1 * sympy.Pow(sympy.E, expr2)
simplified_expr = sympy.powsimp(old_expr)

print("old expr:", sympy.srepr(old_expr))
print("simplified expr:", sympy.srepr(simplified_expr))

It outputs:

old expr: Mul(exp(Symbol('T')), exp(UnevaluatedExpr(Symbol('T'))))
simplified expr: Mul(exp(Symbol('T')), exp(UnevaluatedExpr(Symbol('T'))))

But I would expect it to output this:

old expr: Mul(exp(Symbol('T')), exp(UnevaluatedExpr(Symbol('T'))))
simplified expr: Mul(exp(Add(Symbol('T')), UnevaluatedExpr(Symbol('T')))))