#3399 trigreduce gives malformed property list error

[bigfooted]

I try to simplify a horrible trig expression:

expr:-(2*(B*atan(((A*b+A*a-B)*(cos(B*x)*sin(A*y)+sin(B*x)*cos(A*y)))/(sqrt(A^2*b^2-2*A*B*b-A^2*a^2+B^2)*(sin(B*x)*sin(A*y)-cos(B*x)*cos(A*y)-1)))
    +sqrt(A^2*b^2-2*A*B*b-A^2*a^2+B^2)*atan((cos(B*x)*sin(A*y)+sin(B*x)*cos(A*y))/(sin(B*x)*sin(A*y)-cos(B*x)*cos(A*y)-1))))
 /(A*B*sqrt(A^2*b^2-2*A*B*b-A^2*a^2+B^2));

So, I try trigreduce:

 trigreduce(expr);

malformed property list: (|$b|
((MEXPT SIMP)
((MPLUS SIMP)
((MEXPT SIMP)
((MPLUS SIMP) ((MEXPT SIMP) |$b| 2)
((MTIMES SIMP) -1 ((MEXPT SIMP) |$a| 2)
((MEXPT SIMP) $A 2))
((MTIMES SIMP) -2 |$a| |$b| $B)
((MTIMES SIMP) ((MEXPT SIMP) |$a| 2)
((MEXPT SIMP) $B 2)))
((RAT SIMP) 1 2))
((MTIMES SIMP)
((MEXPT SIMP)
((MPLUS SIMP) ((MEXPT SIMP) |$b| 2)
((MTIMES SIMP) -1 ((MEXPT SIMP) |$a| 2)
((MEXPT SIMP) $A 2))
((MTIMES SIMP) -2 |$a| |$b| $B)
((MTIMES SIMP) ((MEXPT SIMP) |$a| 2)
((MEXPT SIMP) $B 2)))
((RAT SIMP) 1 2))
((%COS SIMP)
((MPLUS SIMP) ((MTIMES SIMP) |$b| $X)
((MTIMES SIMP) |$a| $Y)))))
-1)
((%SIN SIMP)
((MPLUS SIMP) ((MTIMES SIMP) |$b| $X)
((MTIMES SIMP) |$a| $Y)))).

trigsimp and trigexpand keep the expression unchanged.

[Robert Dodier]

I think this is the same error:

(%i1) trigreduce(atan(tan(x + y + z)));

Maxima encountered a Lisp error:

 malformed property list: ($X $Y $Z).

I'm working on a bug fix, I'll keep you posted.

[Robert Dodier]

Fixed by commit 30ed02e0. Closing this report. Thanks for your help.