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Re: Help with Identities

• To: mathgroup at smc.vnet.net
• Subject: [mg65599] Re: [mg65585] Help with Identities
• From: "David Park" <djmp at earthlink.net>
• Date: Mon, 10 Apr 2006 02:31:19 -0400 (EDT)
• Sender: owner-wri-mathgroup at wolfram.com

Sven,

Is this what you mean?

Simplify[Log[x/y] == Log[x] - Log[y], x > 0 && y > 0]
True

Mathematica doesn't say the unsimplified expression is False. It simply
leaves it unchanged.

David Park
djmp at earthlink.net
http://home.earthlink.net/~djmp/


From: Sven C. Koehler [mailto:schween at snafu.de]
To: mathgroup at smc.vnet.net


Hello!

As an occasional mathematican, I sometimes forget that i.e.

Log[x/y] is very similar to Log[x] / Log[y]

Is there some way in Mathematica to see how an mathematical
expression could look like alternatively?  (Something like the  opposite
of Simplify.)

And then I wonder why

Log[x/y] === Log[x] - Log[y]

is False.  Can I instruct Mathematica to explain why this is False?

Best wishes,

Sven