trigreduce(sinh(z)^4)



Hi,

  This is a bug report, but I haven't been able to get through to
  SourceForge.net for a couple of days.

  There is an erroneous reduction rule for a hyperbolic multiple-angle
  formula:
  
(C1) trigreduce(sinh(z)^4);
			 - COSH(4 z) + 4 COSH(2 z) - 3
(D1) 			 -----------------------------
				       8

  This is -1 times the correct answer.  The corresponding expansion is
  correct:

(C2) trigsimp(trigexpand(%));
					4
(D2) 				  - SINH (z)

  i.e.

(C4) trigsimp(trigexpand(trigreduce(sinh(z)^4)));
					4
(D4) 				  - SINH (z)

  Cosh(z)^4, sin(z)^4, and sinh(z)^n (n=2, 3, 5, 6) are all reduced
  correctly, but sinh(z)^8 has a similar error.
  
Geordie McBain
School of Aerospace, Mechanical, & Mechatronic Engineering

Maxima version: 5.9.0rc3
Maxima build date: 16:9 10/29/2002
host type: i386-redhat-linux-gnu
lisp-implementation-type: CLISP
lisp-implementation-version: 2.29 (released 2002-07-25) (built on localhost.localdomain [127.0.0.1])