Document the optional prefix to `calc-yank'.

* doc/misc/calc.texi (Yanking into the Stack): Document the optional
prefix to `calc-yank'.
* lisp/calc/calc-yank.el (calc-yank): Ensure that things killed from
the Calc buffer are yanked back unchanged.

2 files changed, 14 insertions, 1 deletions

diff --git a/doc/misc/calc.texi b/doc/misc/calc.texi
index ecf2ef9e5c2..8579d0f16f5 100644
--- a/doc/misc/calc.texi
+++ b/doc/misc/calc.texi
@@ -29903,6 +29903,19 @@ number in its displayed form, 3.142.  (Since the default display modes
 show all objects to their full precision, this feature normally makes no
 difference.)
 
+The @kbd{C-y} command can be given a prefix, which will interpret the
+text being yanked with a different radix.  If the text being yanked can be
+interpreted as a binary, octal, hexadecimal, or decimal number, then a
+prefix of @kbd{2}, @kbd{8}, @kbd{6} or @kbd{0} will have Calc
+interpret the yanked text as a number in the appropriate base.  For example, 
+if @samp{111} has just been killed and is yanked into Calc with a command
+of @kbd{C-2 C-y}, then the number @samp{7} will be put on the stack.
+If you use the plain prefix @kbd{C-u}, then you will be prompted for a
+base to use, which can be any integer from 2 to 36.  If Calc doesn't
+allow the text being yanked to be read in a different base (such as if
+the text is an algebraic expression), then the prefix will have no
+effect.
+
 @node Saving Into Registers, Inserting From Registers, Yanking Into Stack, Kill and Yank
 @section Saving into Registers
 
diff --git a/lisp/calc/calc-yank.el b/lisp/calc/calc-yank.el
index c93b64b6436..cd447500ffe 100644
--- a/lisp/calc/calc-yank.el
+++ b/lisp/calc/calc-yank.el
@@ -195,7 +195,7 @@ alteration."
                        (concat radix-notation "\\&")
                        thing-raw))
                   thing-raw)))))
-      (if (eq (car-safe calc-last-kill) thing)
+      (if (eq (car-safe calc-last-kill) thing-raw)
           (cdr calc-last-kill)
         (if (stringp thing)
             (let ((val (math-read-exprs (calc-clean-newlines thing))))