subst command in RPN mode (bug ?)

subst command in RPN mode (bug ?) - Printable Version

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subst command in RPN mode (bug ?) - Philippe - 08-12-2015 05:15 PM

Hello,

I would like to report the following behavior :

In home view and in textbook entry, subst('2*Q', 'Q=2') gives 4 as expected.
However, in RPN entry :

'2*Q' Enter
'Q=2' Enter
subst(2) Enter

Returns
"subst(2*Q, (Q==2)) Error: Bad argument type"

Do I miss something? Do you confirms it's a bug ?
Thanks
Philippe

RE: subst command in RPN mode (bug ?) - Tim Wessman - 08-12-2015 05:29 PM

Guessing it has something to do with how the arguments are being fed into the CAS. Probably something interacting with auto-evalation on the CAS side. In the list.

Thanks.

Note that the | (where) operator works fine here though without issue.

RE: subst command in RPN mode (bug ?) - Fortin - 08-12-2015 07:20 PM

This behavior changed from =(Q,2) to Q==2 pretty recently. I forget the specific release number though. This was also the release that changed the = behavior in Adv Graphing to == ... 7820 maybe? ...don't know if that helps...

RE: subst command in RPN mode (bug ?) - Didier Lachieze - 08-12-2015 07:56 PM

(08-12-2015 05:15 PM)Philippe Wrote: In home view and in textbook entry, subst('2*Q', 'Q=2') gives 4 as expected.
However, in RPN entry :

'2*Q' Enter
'Q=2' Enter
subst(2) Enter

The single quotes are lost when you press enter, on the stack you don't have '2*Q' but just 2*Q.
So you need to add another set of single quotes or double
quotes around the parameters to make it work , for example :

"'2*Q'" Enter
"'(Q=2)'" Enter
subst(2)

RE: subst command in RPN mode (bug ?) - Marcelo Vanti - 08-12-2015 08:55 PM

(08-12-2015 07:56 PM)Didier Lachieze Wrote: "'2*Q'" Enter
"'(Q=2)'" Enter
subst(2)

it works here, indeed, if I use q (lowercase letter) rather than Q:
"2*q"
"q=2"
CAS.subst(2) ==> 4

RE: subst command in RPN mode (bug ?) - Didier Lachieze - 08-12-2015 10:15 PM

(08-12-2015 08:55 PM)Marcelo Vanti Wrote:
(08-12-2015 07:56 PM)Didier Lachieze Wrote: "'2*Q'" Enter
"'(Q=2)'" Enter
subst(2)

it works here, indeed, if I use q (lowercase letter) rather than Q:
"2*q"
"q=2"
CAS.subst(2) ==> 4

It works as long as q is not defined. But if you create q, for ex by storing 0 to q then the subst command will return 0 as 2*q will be evaluated to 0 before the substitution can be done. To pass 2*q to the CAS for the substitution you need the single quotes inside the double quotes, or two levels of single quotes.

RE: subst command in RPN mode (bug ?) - Didier Lachieze - 08-12-2015 10:24 PM

(08-12-2015 08:55 PM)Marcelo Vanti Wrote:
(08-12-2015 07:56 PM)Didier Lachieze Wrote: "'2*Q'" Enter
"'(Q=2)'" Enter
subst(2)

it works here, indeed, if I use q (lowercase letter) rather than Q:
"2*q"
"q=2"
CAS.subst(2) ==> 4

RE: subst command in RPN mode (bug ?) - Marcelo Vanti - 08-13-2015 12:36 PM

(08-12-2015 10:24 PM)Didier Lachieze Wrote: It works as long as q is not defined. But if you create q, for ex by storing 0 to q then the subst command will return 0 as 2*q will be evaluated to 0 before the substitution can be done. To pass 2*q to the CAS for the substitution you need the single quotes inside the double quotes, or two levels of single quotes.

You're right. I did not know the possibility of working with single quotes within double quotes, for replacement. Thanks for the tip.