Evaluation of "standard" style math expresssions.

Evaluation of "standard" style math expresssions.

[Alex Polite]

Hi there.

I know how to evaluate mathematical expressions expressed in lisp in
any emacs buffer.  (eg (+ 17 42))

But I'd like to be able to eval expression where the notation is the
kind you learn in school (eg (17 + 42))

How do I do it?

-- 
Alex Polite
http://polite.se

Re: Evaluation of "standard" style math expresssions.

[Joakim Hove]

Alex Polite <m4@polite.se> writes:


> But I'd like to be able to eval expression where the notation is the
> kind you learn in school (eg (17 + 42))
>
> How do I do it?

Well,

you just can't (I think) evaluate (17 + 42) as a lisp expression. What
you of course could do was write a lisp function which parsed such
expressions, and then evaluated them, but I guess that is not what you
want.


Joakim

-- 
Joakim Hove
hove AT ift uib no
+47 (55 5)8 27 90
http://www.ift.uib.no/~hove/

Re: Evaluation of "standard" style math expresssions.

[Marco Parrone]

Alex Polite on 21 Sep 2004 11:48:13 GMT writes:

> I know how to evaluate mathematical expressions expressed in lisp in
> any emacs buffer.  (eg (+ 17 42))
>
> But I'd like to be able to eval expression where the notation is the
> kind you learn in school (eg (17 + 42))
>
> How do I do it?

you can pipe the expression to bc.

for example on a line you have

1 + 2 * 3

you can set the mark `C-SPC' at the beginning of the line, then move
the point in the next line `C-n', then pipe the line to bc `M-| bc RET'

try with

9 / 2

you get 4, you may want to do this instead

scale=1
9 / 2

(set the mark at the beginning of the first line and move the point
after the second), so to get `4.5'.

for more informations about bc syntax, do `M-x man RET bc RET'.

-- 
Marco Parrone <marc0@autistici.org>
fingerprint: F7D4 527B DE97 4090 657B  6E4E 8B63 1167 (4507 0AD6)

Re: Evaluation of "standard" style math expresssions.

[Alex Polite]

On tis, sep 21, 2004 at 12:07:56 +0000, Marco Parrone wrote:
> you can pipe the expression to bc.
> 

ahh. exactly what i wanted. I'll wrap bc so that I want have to input
the scale thing every time.

thanks.
alex

-- 
Alex Polite
http://polite.se

Re: Evaluation of "standard" style math expresssions.

[Albert Reiner]

[Alex Polite <m4@polite.se>, 21 Sep 2004 11:48:13 GMT]:
> Hi there.
> 
> I know how to evaluate mathematical expressions expressed in lisp in
> any emacs buffer.  (eg (+ 17 42))
> 
> But I'd like to be able to eval expression where the notation is the
> kind you learn in school (eg (17 + 42))

M-x calc 1 7  + 4 2 RET; q to quit calc again.

Or if you have the maxima CAS <http://maxima.sourceforge.net/>
installed, you can simply use maxima-minor-mode or maxima-minibuffer
to do much more than adding numbers.  (Don't know whether this works
on windows.)

Albert.

Re: Evaluation of "standard" style math expresssions.

[Stefan Monnier]

>> I know how to evaluate mathematical expressions expressed in lisp in
>> any emacs buffer.  (eg (+ 17 42))
>> 
>> But I'd like to be able to eval expression where the notation is the
>> kind you learn in school (eg (17 + 42))

> M-x calc 1 7  + 4 2 RET; q to quit calc again.

Hmm...that doesn't work here.  It works with M-x calculator, but with
M-x calc it starts `Calc' which by default uses RPN notation.


        Stefan

Re: Evaluation of "standard" style math expresssions.

[Jay Belanger]

Stefan Monnier <monnier@iro.umontreal.ca> writes:
...
>> M-x calc 1 7  + 4 2 RET; q to quit calc again.
>
> Hmm...that doesn't work here.  It works with M-x calculator, but with
> M-x calc it starts `Calc' which by default uses RPN notation.

Okay; how 'bout
M-x calc '17+42 RET
or even
M-x quick-calc (often M-# q)
which will prompt you for an expression in the minibuffer.

Jay

Re: Evaluation of "standard" style math expresssions.

[Albert Reiner]

> > M-x calc 1 7  + 4 2 RET; q to quit calc again.
> 
> Hmm...that doesn't work here.  It works with M-x calculator, but with
> M-x calc it starts `Calc' which by default uses RPN notation.

Works here (GNU Emacs 21.2.1 (i386-redhat-linux-gnu, X toolkit, Xaw3d
scroll bars) of 2003-02-20 on porky.devel.redhat.com), but it there
may be some "smart" installation at work, putting calc in algebraic
mode or so.

Albert.

Re: Evaluation of "standard" style math expresssions.

[Stefan Monnier]

>> > M-x calc 1 7  + 4 2 RET; q to quit calc again.
>> 
>> Hmm...that doesn't work here.  It works with M-x calculator, but with
>> M-x calc it starts `Calc' which by default uses RPN notation.

> Works here

Just because you don't have any other command that starts with `calc'.
The command you execute is M-x calculator (the "ulator" part is filled by
Emacs for you because there's no other choice in your case).
Emacs-CVS comes with a new package that adds a command M-x calc which is
another (much more sohisticated) calculator and this one uses RPN
by default.


        Stefan