Re: Question on using eval...

[wraithx@morpheus.net]

On 1/2/2023 4:09 PM, Bill Allombert wrote:
> On Mon, Jan 02, 2023 at 03:31:00PM -0600, wraithx@morpheus.net wrote:
> > Hello,
> >
> > I've run into an issue using the "eval" function.  I'm trying to check two
> > expressions for symbolic equality.  But, I run into a problem when I use the
> > exponent operator.  Is this a valid use for the eval function?  Is there
> > another way to check if two expressions are equal?  Thank you for any help
> > you can provide!
>
> Dear David,
>
> The eval function does not work like in Maple.
> Writing
> ? eval("something")
> has the same effect as
> ? something.
> so it is not useful with string constants.
>
> > gp > a
> > %1 = a
> > gp > b
> > %2 = b
> > gp > c
> > %3 = c
> > gp > eval("(a/b)+c == (a-b)+c")
>
>   gp> (a/b)+c == (a-b)+c
>   would do the same thing faster.

I did see that I could just write the expression on the gp command line, but 
unfortunately, I am using code to generate these expressions and so I only have 
them available as strings.

Do you know of a way to compare two expressions in pari/gp (checking for 
equality) when each expression is stored in a string?  Hopefully a way that 
includes the exponent operator?

-David C.