Re: AW: Re: Expanding Trig Power Identities
- To: mathgroup at smc.vnet.net
- Subject: [mg30402] Re: AW: [mg30365] Re: [mg30348] Expanding Trig Power Identities
- From: BobHanlon at aol.com
- Date: Wed, 15 Aug 2001 01:04:08 -0400 (EDT)
- Sender: owner-wri-mathgroup at wolfram.com
In a message dated 2001/8/14 8:44:10 AM, Matthias.Bode at oppenheim.de writes: >I tried Bob Hanlon's TrigReduce Table changing n from "{n, 4}" to "{n, >1, 3, >0.5}": > >Table[{y = Sin[a]*Sin[b]^n, "=", TrigReduce[y]}, {n, 1, 3, 0.5}] // >TableForm > >and neither the integer nor the non-integer exponent expressions evaluated >whereas the original example "{n, 4}" evaluates just fine. Why? > If the step is an approximate number then everything after the first value (even if it is exact) is approximate. Table[k, {k, 1, 3, 0.5}] {1, 1.5, 2., 2.5, 3.} The TrigReduce rules require certain forms (exact powers). Use an exact (rational) step Table[{y = Sin[a]*Sin[b]^n, "=", TrigReduce[y]}, {n, 1, 3, 1/2}] //Factor // TableForm or Table[{y = Sin[a]*Sin[b]^Rationalize[n], "=", TrigReduce[y]}, {n, 1, 3, 0.5}] //Factor//TableForm Bob Hanlon Chantilly, VA USA