[Date Index] [Thread Index] [Author Index]

Re: TraditionForm Appears to be Inconsistent

• To: mathgroup at smc.vnet.net
• Subject: [mg99602] Re: TraditionForm Appears to be Inconsistent
• From: Bill Rowe <readnews at sbcglobal.net>
• Date: Sat, 9 May 2009 03:19:32 -0400 (EDT)

On 5/7/09 at 6:40 AM, uk.org.microserf at googlemail.com wrote:

>The Mathematica 7 documentation says that

>TraditionalForm[Exp[I \[Theta]] == Cos[\[Theta]] + I Sin[\[Theta]]]

>will display the expression in traditional form, and indeed it does.
>However, the following evaluates the expression and then displays
>True in traditional form:

>TraditionalForm[Cos[x] == Sin[x + \[Pi]/2]]

>Why is TraditionalForm behaving differently in these two apparently
>identical situations, and how can I get Mathematica to display this
>trigonometric identity in traditional form?

TraditionalForm is not behaving differently. Mathematica by
default evaluates everything it can. When you do
TraditionalForm[Cos[x] == Sin[x + \[Pi]/2]], Mathematica
evaluates the argument to True and the result is the same as if
you had done TraditionalForm[True]

To get what you want you have to tell Mathematica not to
evaluate the argument. Specifically, you need to use HoldForm.
That is:

TraditionalForm[HoldForm[Cos[x] == Sin[x + \[Pi]/2]]]

will give you the display you want.