# Installing racket-cas

**URL:** <https://racket.discourse.group/t/installing-racket-cas/3367>\
**Category:** Questions & Answers\
**Created:** [November 28, 2024, 6:13am UTC](https://racket.discourse.group/t/installing-racket-cas/3367 "2024-11-28T06:13:14Z")\
**Posts on this page:** 19\
**Page:** 1

<div class="post-metadata">

**Author:** ![AlexG](https://avatars.discourse-cdn.com/v4/letter/a/ecc23a/32.png) [@AlexG](https://racket.discourse.group/u/AlexG)\
**Post date:** [November 28, 2024, 6:13am UTC](https://racket.discourse.group/t/installing-racket-cas/3367/1 "2024-11-28T06:13:14Z")

</div>

I finally got round to trying @soegaard 's `racket-cas` and on the whole it seems OK but I'm not sure I've installed it correctly, there are some minor issues and the docs seem unclear.

I downloaded the zip from github and ran drracket from its directory.  
Is it supposed to be installed as a package under raco? I didn't do that, maybe I was supposed to.

To get it to run I then had to modify main.rkt a bit, and then loaded that up into my DrRacket IDE. Here's the file:

```scheme
#lang racket
(require "racket-cas.rkt")
(require "repl.rkt")

(provide (all-from-out "racket-cas.rkt"))

```

When I run this, the greeting appears OK, and the basic commands see to work fine, eg

```scheme
> (tex (expand '(expt (+ a b) 2)))
"$a^{2}+b^{2}+2\\cdot {a\\cdot b}$"

```

Typing plain `x` `y` or `z` also correctly reads them as `'x` `'y` or `'z`

What does _not_ happen is automatic simplification, which the docs say should happen. However if I explicitly request simplification, it seems OK.

```scheme
> `(+ 3 a 2 x (* 4 x))
'(+ 3 a 2 x (* 4 x))
> (simplify `(+ 3 a 2 x (* 4 x)))
'(+ 5 a (* 5 x))

```

Any suggestions?  
(Especially if this should be installed as a package? The suggestion to use the form  
`(require racket-cas/repl)`  
instead of how I did it makes me think so.)

Thanks!

---

<div class="post-metadata">

**Author:** ![soegaard](https://yyz2.discourse-cdn.com/free1/user_avatar/racket.discourse.group/soegaard/32/19_2.png) [@soegaard](https://racket.discourse.group/u/soegaard)\
**Post date:** [November 28, 2024, 11:12am UTC](https://racket.discourse.group/t/installing-racket-cas/3367/2 "2024-11-28T11:12:07Z")

</div>

Thanks for taking the time to test `racket-cas`.

You are right there is an issue with the `quasiquote` when required.  
It's a scope issue (I believe) - maybe someone can spot the problem [see later].

However, you can open the file `repl.rkt` directly and run it.  
Then quasiquote, `, will work in the repl:

 ![image](https://global.discourse-cdn.com/free1/uploads/racket/original/2X/3/348dec73d41a98ebcaab132a04288def68da06bd.jpeg)

Note however, that _automatic simplification_ and `simplify` is two different things. The automatic simplifier only does "small stuff" (adds numbers, collect equal terms, sort the terms etc.).

The functions in `racket-cas` usually expect their inputs to be _normalized_.  
If the inputs are normalized, the outputs are also normalized.  
Therefore the automatic simplifier (aka `normalize`) must be used on inputs  
before calling many of the functions.

In the repl it is more convenient to use quasiquote `than it is to write`normalize` all the time.

But, back to the macro problem. The "make quasiquote do automatic simplification" macro is defined in [1].

The question is why it works when used in "repl.rkt" but not when required from the repl?

```scheme
(module+ start
  (provide quote quasiquote)
  (require (submod ".."))
  (require (prefix-in old: (only-in racket/base quote quasiquote)))
  ; In the REPL it can be convenient to change the meaning of ' 
  ; to automatic normalization:
  (define-syntax (quote stx) 
    (syntax-case stx () [(_ . datum) #'(normalize (old:quote . datum))]))
  (define-syntax (quasiquote stx) 
    (syntax-case stx () [(_ . datum) #'(normalize (old:quasiquote . datum))])))

; (let () (define f '(* x x)) `(* x ,f))  

; This macro doesn't work as expected ... why?
(define-syntax (repl stx) 
  (syntax-case stx () 
    [_ (with-syntax ([req (datum->syntax stx 'require)])
         (syntax/loc stx (req (submod "." start))))]))

```

[1] [racket-cas/racket-cas/racket-cas.rkt at master · soegaard/racket-cas · GitHub](https://github.com/soegaard/racket-cas/blob/master/racket-cas/racket-cas.rkt)

---

<div class="post-metadata">

**Author:** ![AlexKnauth](https://yyz2.discourse-cdn.com/free1/user_avatar/racket.discourse.group/alexknauth/32/242_2.png) [@AlexKnauth](https://racket.discourse.group/u/AlexKnauth)\
**Post date:** [November 28, 2024, 3:12pm UTC](https://racket.discourse.group/t/installing-racket-cas/3367/3 "2024-11-28T15:12:47Z")

</div>

Where you're doing `(provide (all-from-out "racket-cas.rkt"))`, does it help to also provide all-from-out `"repl.rkt"`?

---

<div class="post-metadata">

**Author:** ![AlexG](https://avatars.discourse-cdn.com/v4/letter/a/ecc23a/32.png) [@AlexG](https://racket.discourse.group/u/AlexG)\
**Post date:** [November 28, 2024, 7:01pm UTC](https://racket.discourse.group/t/installing-racket-cas/3367/4 "2024-11-28T19:01:20Z")

</div>

Thanks for all that, Axel!  
Yes, indeed, opening `repl.rkt` instead of `main.rkt` fixes the normalization/auto-simplification issue  
(@AlexKnauth , no, just adding `all-from-out` does not fix it, but it doesn't matter, since you can just launch off the repl.rkt file)

Looking forward to testing it and seeing how it's been implemented!

There is one more little thing I found, I think it may be due to an update in Racket since it was written, I'm guessing it was a keyword parameter change

```scheme
> (render (expand '(expt (+ a b) 2)))
. . racket-cas.rkt:2065:23: application: required keyword argument not supplied
  procedure: latex->pict
  required keyword: #:preamble
  arguments...:

```

Any ideas? - it would be nice to have a renderer that can be shown off...

---

<div class="post-metadata">

**Author:** ![AlexKnauth](https://yyz2.discourse-cdn.com/free1/user_avatar/racket.discourse.group/alexknauth/32/242_2.png) [@AlexKnauth](https://racket.discourse.group/u/AlexKnauth)\
**Post date:** [November 28, 2024, 7:15pm UTC](https://racket.discourse.group/t/installing-racket-cas/3367/5 "2024-11-28T19:15:50Z")

</div>

Where are you trying to use the `repl` macro? It seems like the `"."` in the submod would only work if it's already in the same module anyway.

---

<div class="post-metadata">

**Author:** ![soegaard](https://yyz2.discourse-cdn.com/free1/user_avatar/racket.discourse.group/soegaard/32/19_2.png) [@soegaard](https://racket.discourse.group/u/soegaard)\
**Post date:** [November 28, 2024, 8:42pm UTC](https://racket.discourse.group/t/installing-racket-cas/3367/6 "2024-11-28T20:42:53Z")

</div>

I think, the problem that `render` used to be defined in `racket-cas` but was removed.  
Now it calls a `render` from `latex-pict`, which is broken.  
[I'll fix that.]

In the mean time, you can paste this definition into the repl to get a `render`.

 ![image](https://global.discourse-cdn.com/free1/uploads/racket/original/2X/c/cd32e4407f9946066da58f4068baa18bfc27344e.jpeg)

```scheme
    (begin (require latex-pict pict)
                 (define (render u)
                   (define (strip$ x) (substring x 1 (- (string-length x) 1)))
                   (pict->bitmap (scale (tex-math (strip$ (tex u))) 2))))

```

---

<div class="post-metadata">

**Author:** ![AlexG](https://avatars.discourse-cdn.com/v4/letter/a/ecc23a/32.png) [@AlexG](https://racket.discourse.group/u/AlexG)\
**Post date:** [November 28, 2024, 9:45pm UTC](https://racket.discourse.group/t/installing-racket-cas/3367/7 "2024-11-28T21:45:02Z")

</div>

Erm, almost but not quite

```scheme
> (begin (require latex-pict pict)
                 (define (render u)
                   (define (strip$ x) (substring x 1 (- (string-length x) 1)))
                   (pict->bitmap (scale (tex-math (strip$ (tex u))) 2))))
> (render (normalize '(+ x 2 a 3 (* 4 x))))
exec failed (No such file or directory; errno=2)
. . ../../usr/share/racket/collects/racket/private/kw.rkt:1386:57: open-input-file: cannot open input file
  path: /var/tmp/latex2pdf-6d322b6d01941cdd976b954807b0591c.log
  system error: No such file or directory; errno=2

```

You can see it flash momentarily as it tries to open a rendering window, but then it reports the above error about not being able to find some log file, no idea what that is, I'm afraid. Permissions?

Anyway it really is not a high priority for me, I'm more than happy to wait till it's fixed, but it certainly would be nice to have, once everything's going. Just thought I'd let you know.

---

<div class="post-metadata">

**Author:** ![soegaard](https://yyz2.discourse-cdn.com/free1/user_avatar/racket.discourse.group/soegaard/32/19_2.png) [@soegaard](https://racket.discourse.group/u/soegaard)\
**Post date:** [November 28, 2024, 10:14pm UTC](https://racket.discourse.group/t/installing-racket-cas/3367/8 "2024-11-28T22:14:31Z")

</div>

The package `latex-pict` uses `pdflatex` and a couple of latex libraries.  
Maybe something is configured differently on your computer?  
If you are using a complete, newish TeXLive, I'd expect everything to work.  
Marc had to install some extra packages to get everything to work though.

See

> [@Plot with subscripts, superscripts, and more general latex in labels](https://racket.discourse.group/t/plot-with-subscripts-superscripts-and-more-general-latex-in-labels/373/6):
>
> You probably meant pdflatex foo.tex, no? That throws an error that it can't find standalone.cls, so I installed it with tlmgr install standalone, after which it complains about not knowing preview.sty, so I tlmgr install preview and voila. It works. Reading the documentation for latex-pict, I now realize that I should have checked that both of those are installed, but it was not crystal clear to me that those were requirements. Maybe make it even more obvious by saying "Ensure that you have the…

I expect `pdflatex` is in the path?

---

<div class="post-metadata">

**Author:** ![AlexG](https://avatars.discourse-cdn.com/v4/letter/a/ecc23a/32.png) [@AlexG](https://racket.discourse.group/u/AlexG)\
**Post date:** [November 28, 2024, 10:55pm UTC](https://racket.discourse.group/t/installing-racket-cas/3367/9 "2024-11-28T22:55:45Z")

</div>

`pdflatex` was not on the path.

It is now, it's still failing, but with less error output 😁

```scheme
(render (normalize '(+ x 2 a 3 (* 4 x))))
. . ../../usr/share/racket/collects/racket/private/kw.rkt:1386:57: latex failed

```

I'll look into it later, I'm more involved with the math now.

====  
PS. The offending line was:

```scheme
                                ;; caller didn't lift expressions out
                                (let ([ids (generate-temporaries args)])
>1386....................>>> #`(let #,(map list ids
                                          (map hide-binding-name args))
                                              #,(k ids)))

```

if that helps at all

---

<div class="post-metadata">

**Author:** ![cadence](https://yyz2.discourse-cdn.com/free1/user_avatar/racket.discourse.group/cadence/32/998_2.png) [@cadence](https://racket.discourse.group/u/cadence)\
**Post date:** [November 29, 2024, 2:13am UTC](https://racket.discourse.group/t/installing-racket-cas/3367/10 "2024-11-29T02:13:45Z")

</div>

Which editor are you using in your screenshot? Mine doesn't really look like that in DrRacket or Emacs, and I'm wondering if there's another editor you're using that I haven't tried.

---

<div class="post-metadata">

**Author:** ![soegaard](https://yyz2.discourse-cdn.com/free1/user_avatar/racket.discourse.group/soegaard/32/19_2.png) [@soegaard](https://racket.discourse.group/u/soegaard)\
**Post date:** [November 29, 2024, 4:06pm UTC](https://racket.discourse.group/t/installing-racket-cas/3367/11 "2024-11-29T16:06:16Z")

</div>

@cadence

It's just Emacs.  
I have over time stolen bits and pieces from Eli, Greg and Bogdan  
and added keybindings that work more-or-less like DrRacket.

See:

> <https://gist.github.com/soegaard/40b1425f9c5fc206de3f8244ff996328>

---

<div class="post-metadata">

**Author:** ![AlexG](https://avatars.discourse-cdn.com/v4/letter/a/ecc23a/32.png) [@AlexG](https://racket.discourse.group/u/AlexG)\
**Post date:** [December 14, 2024, 9:28pm UTC](https://racket.discourse.group/t/installing-racket-cas/3367/12 "2024-12-14T21:28:09Z")

</div>

@soegaard Hey Jens,  
I just wanted to say that the racket-cas library is really nice, works well and has saved me a ton of work for now!

I mean, I know everybody wants to write their own, and so do I 🤪 but until then, this is really super.

Many, many thanks!

---

<div class="post-metadata">

**Author:** ![soegaard](https://yyz2.discourse-cdn.com/free1/user_avatar/racket.discourse.group/soegaard/32/19_2.png) [@soegaard](https://racket.discourse.group/u/soegaard)\
**Post date:** [December 14, 2024, 9:32pm UTC](https://racket.discourse.group/t/installing-racket-cas/3367/13 "2024-12-14T21:32:15Z")

</div>

That's great to hear!

---

<div class="post-metadata">

**Author:** ![AlexG](https://avatars.discourse-cdn.com/v4/letter/a/ecc23a/32.png) [@AlexG](https://racket.discourse.group/u/AlexG)\
**Post date:** [December 14, 2024, 9:45pm UTC](https://racket.discourse.group/t/installing-racket-cas/3367/14 "2024-12-14T21:45:35Z")

</div>

Yeah, especially the subst functionality, which allows me to combine it with normal Racket functional code is a boon.  
I'm sure I'll be plaguing you with some questions in the future, and once I've got my head around it a bit, I'll be happy to look through the source, see if there's anywhere I can help!  
Have a great Festive Season...

```scheme
(define (unapply expr var) (λ(x) (subst expr var x)))
((unapply '(+ x (* 2 y)) 'x) 3)
==> '(+ 3 (* 2 y))
((unapply '(+ x (* 2 y)) 'y) 3)
==> '(+ 6 x)

```

---

<div class="post-metadata">

**Author:** ![AlexG](https://avatars.discourse-cdn.com/v4/letter/a/ecc23a/32.png) [@AlexG](https://racket.discourse.group/u/AlexG)\
**Post date:** [December 17, 2024, 4:45pm UTC](https://racket.discourse.group/t/installing-racket-cas/3367/15 "2024-12-17T16:45:00Z")

</div>

As I said, I've been getting along with racket-cas faster than I thought I would.  
The idea is to make a generalised math package, gjs-stylee, perhaps ultimately a bit like scmutils. For this, I need to be able to move transparently between numeric and symbolic code. Also I need functions to evaluate "normally" when dealing with inexact values, but symbolically when dealing with exact or symbolic ones. Like my 80s TI-Voyage on its puny m68k, is that too much to ask? 😄  
Anyway, the racket-cas library seems really easy to interact with , I've managed to encapsulate it acceptably so far. See, the racket-cas notation is "hidden", expressions are generated by regular functions.

```scheme
; sorry, not done expt yet  
(define (power expr i) (expand ((repeat-apply (curry * expr) i) 1)))
> (power (+ 'x 1) 6)
(+ 1 (* 6 x) (* 15 (expt x 2)) (* 20 (expt x 3)) (* 15 (expt x 4)) (* 6 (expt x 5)) (expt x 6))

```

@soegaard Really nice to have those `expand` and `distribute` functionalities so easily available but (if I may ask) did you deliberately not incorporate them into simplification routines? Just out of curiosity.

Also how can I get the docs into html or pdf or whatever? I tried running

```scheme
scribble --html racket-cas.scrbl

```

but to no avail. I also tried to pass it that info file, but I must be doing something basically wrong.

---

<div class="post-metadata">

**Author:** ![soegaard](https://yyz2.discourse-cdn.com/free1/user_avatar/racket.discourse.group/soegaard/32/19_2.png) [@soegaard](https://racket.discourse.group/u/soegaard)\
**Post date:** [December 17, 2024, 5:12pm UTC](https://racket.discourse.group/t/installing-racket-cas/3367/16 "2024-12-17T17:12:18Z")

</div>

> Really nice to have those `expand` and `distribute` functionalities so easily available but (if I may ask) did you deliberately not incorporate them into simplification routines? Just out of curiosity.

Yes. Consider `(x+y)^100000`. This is a small expression whose expansion is large. This choice matches Mathematica, NSpire and other.

I'll need to check that's the issue with the docs.

Btw - since you mention that you also need numerical calculations.  
The `compile` function exported by `racket-cas` can be used to convert S-expressions into normal, callable functions.

Example from the README.

```scheme
We can use standard plot library to draw a few graphs of the Taylor polynomials.
The plot library expects standard Racket functions from number to number.
The function compile will turn a symbolic expression into a normal Racket function.
    > (require plot)
    > (plot (list (function (compile (taylor '(sin x) x 0 5)) #:color "green")
                  (function sin #:color "red" -3.14 3.14)))
    <nice graphs appear in DrRacket>

```

---

<div class="post-metadata">

**Author:** ![soegaard](https://yyz2.discourse-cdn.com/free1/user_avatar/racket.discourse.group/soegaard/32/19_2.png) [@soegaard](https://racket.discourse.group/u/soegaard)\
**Post date:** [December 17, 2024, 5:34pm UTC](https://racket.discourse.group/t/installing-racket-cas/3367/17 "2024-12-17T17:34:19Z")

</div>

> [@AlexG](#):
>
> `scribble --html racket-cas.scrbl`

I tried `scribble --html racket-cas.scrbl` and `scribble --pdf racket-cas.scrbl` and they worked for me (at least after running `raco setup`).

Hmm. I can't attach pdfs?

I'll send a mail instead.

---

<div class="post-metadata">

**Author:** ![AlexG](https://avatars.discourse-cdn.com/v4/letter/a/ecc23a/32.png) [@AlexG](https://racket.discourse.group/u/AlexG)\
**Post date:** [December 17, 2024, 5:38pm UTC](https://racket.discourse.group/t/installing-racket-cas/3367/18 "2024-12-17T17:38:34Z")

</div>

Ah, great, thanks, I was about to look into that (compile). Looks useful, especially if the results are faster than whatever clunky solutions.

BTW, teeny typo in readme

```scheme
(compile (taylor '(sin 'x) 'x 0 5))

```

Erm, I never ran `raco setup` first, should I have? What does it set up that isn't already set up?

---

<div class="post-metadata">

**Author:** ![soegaard](https://yyz2.discourse-cdn.com/free1/user_avatar/racket.discourse.group/soegaard/32/19_2.png) [@soegaard](https://racket.discourse.group/u/soegaard)\
**Post date:** [December 17, 2024, 5:42pm UTC](https://racket.discourse.group/t/installing-racket-cas/3367/19 "2024-12-17T17:42:49Z")

</div>

Apropos typo: Sorry, I took the example out of context.  
Earlier in the readme, I have:

```scheme
> (require racket-cas/auto-quote)
> x
'x

```

The auto-quote feature turns unbound references into symbols.  
A feature meant to be used in the repl only.

I don't think it is needed to run `raco setup` first - but I had a new installation and had to before it scribble ran as expected.