[BUG] ob-calc and decimal number in :var [9.7-pre (release_9.6.17-1446-g252971 @ /home/viz/lib/emacs/straight/build/org/)]

[Visuwesh <visuweshm@gmail.com>]

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In emacs -Q, try evaluating the source block

#+BEGIN_SRC calc :var thetarot=1.3
  1/thetarot	
#+END_SRC

and witness the following error:

Debugger entered--Lisp error: (wrong-type-argument listp 1.3)
  nth(2 1.3)
  calc-div-fractions(1 1.3)
  math-div(1 1.3)
  math-mul-or-div(1 1.3 nil t)
  math-combine-prod(1 1.3 nil t t)
  math-simplify-one-divisor((1 1.3) (1.3))
  math-simplify-divisor((1 1.3) (1.3) nil t)
  math-simplify-divide((/ 1 1.3))
  #f(compiled-function (expr) #<bytecode -0xce707cc7797ed02>)((/ 1 1.3))
  math-simplify-step((/ 1 1.3))
  math-simplify((/ 1 1.3))
  calc-normalize-fancy((/ 1 1.3))
  calc-normalize((/ 1 1.3))
  math-evaluate-expr((/ 1 1.3))
  #f(compiled-function (line) #<bytecode -0x1da56b5a0e8d9337>)("1/thetarot")
  mapc(#f(compiled-function (line) #<bytecode -0x1da56b5a0e8d9337>) ("1/thetarot"))
  org-babel-execute:calc("1/thetarot\11" ((:var thetarot . 1.3) (:colname-names) (:rowname-names) (:result-params "replace") (:result-type . value) (:results . "replace") (:exports . "code") (:session . "none") (:cache . "no") (:noweb . "no") (:hlines . "no") (:tangle . "no")))
  org-babel-execute-src-block(nil ("calc" "1/thetarot\11" ((:var thetarot . 1.3) (:colname-names) (:rowname-names) (:result-params "replace") (:result-type . value) (:results . "replace") (:exports . "code") (:tangle . "no") (:hlines . "no") (:noweb . "no") (:cache . "no") (:session . "none")) "" nil 148 "(ref:%s)"))
  org-ctrl-c-ctrl-c(nil)
  funcall-interactively(org-ctrl-c-ctrl-c nil)
  call-interactively(org-ctrl-c-ctrl-c nil nil)
  command-execute(org-ctrl-c-ctrl-c)

This happens because the decimal number 1.3 is not in the format calc
expects.  A VERY DIRTY patch to do this is

diff --git a/lisp/ob-calc.el b/lisp/ob-calc.el
index f36df77ff..6ef09032a 100644
--- a/lisp/ob-calc.el
+++ b/lisp/ob-calc.el
@@ -111,7 +116,7 @@ EL is taken from the output of `math-read-exprs'."
       (if (and (eq 'var (car el)) (member (cadr el) org--var-syms))
 	  (progn
 	    (calc-recall (cadr el))
-	    (prog1 (calc-top 1)
+	    (prog1 (math-read-exprs (format "%S" (calc-top 1)))
 	      (calc-pop 1)))
 	(mapcar #'org-babel-calc-maybe-resolve-var el))
     el))

but unfortunately, I don't have the time currently to polish this up.
If someone doesn't beat me to it, I will send a more polished+tested
patch by the beginning of May (if I get a lot of free time, I can try to
make one in the meanwhile).

Emacs  : GNU Emacs 30.0.50 (build 2, x86_64-pc-linux-gnu, X toolkit, cairo version 1.18.0, Xaw scroll bars)
 of 2024-02-17
Package: Org mode version 9.7-pre (release_9.6.17-1446-g252971 @ /home/viz/lib/emacs/straight/build/org/)