--- Begin Message ---
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Subject: |
24.4.50; problem with built-in function "ldexp" Emacs Ver: 24.4.50.1 |
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Date: |
Mon, 23 Mar 2015 20:29:13 +0000 |
(24.4.50) 3.2 Floating-Point Basics we read:
---------- snip ------------
-- Function: ldexp sig &optional exp
This function returns a floating-point number corresponding to the
significand SIG and exponent EXP.
----------snip -------------
However it is easy to verify that the second argument is not
optional. For example:
(ldexp 5.0)
triggers the error:
*** Eval error *** Wrong type argument: integerp, nil
The code for ldexp in floatfn.c reads:
---------- snip ---------------
DEFUN ("ldexp", Fldexp, Sldexp, 1, 2, 0,
doc: /* Construct number X from significand SGNFCAND and exponent EXP.
Returns the floating point value resulting from multiplying SGNFCAND
(the significand) by 2 raised to the power of EXP (the exponent). */)
(Lisp_Object sgnfcand, Lisp_Object exponent)
{
CHECK_NUMBER (exponent);
return make_float (ldexp (XFLOATINT (sgnfcand), XINT (exponent)));
}
---------- snip -------------
The declaration conforms to that in the manual but nothing seems to have
been done to take into account what happens when `exp' is missing. It
seems to me that there are two possibilities:
EITHER: The declaration in floatfns.c is incorrect and should read:
DEFUN ("ldexp", Fldexp, Sldexp, 1, 1, 0,
....
In which case it will need to be changed and the manual will need to be
changed accordingly.
OR: `exp' is supposed to have a default value (0 say), when the code in
floatfns.c should be changed accordingly. In this case it might still
be a good idea to update the manual to explain that it has this value.
--- End Message ---
0001-Fix-minor-ldexp-issues.patch