[mul.c] don't call mpc_sqr any more when both inputs are the same variable

[mpc.texi,NEWS] document the above change


git-svn-id: svn://scm.gforge.inria.fr/svn/mpc/trunk@1139 211d60ee-9f03-0410-a15a-8952a2c7a4e4

3 files changed, 3 insertions, 6 deletions

diff --git a/NEWS b/NEWS
index f4ca2d7..00e7f30 100644
--- a/NEWS
+++ b/NEWS
@@ -2,6 +2,7 @@ Changes in version 1.0:
   - First release as a GNU package
   - License change: LGPLv3+ for code, GFDLv1.3+ for documentation
   - 0^0, which returned (NaN,NaN) previously, now returns (1,+0),
+  - mpc_mul no longer calls mpc_sqr when the two inputs are the same
   - Bug fixes:
     - div and norm now return a value indicating the effective rounding
       direction, as the other functions.
diff --git a/doc/mpc.texi b/doc/mpc.texi
index dfa74ec..acb4576 100644
--- a/doc/mpc.texi
+++ b/doc/mpc.texi
@@ -863,6 +863,8 @@ For @code{mpc_ui_ui_sub}, @var{op1} is @var{re1} + @var{im1}.
 @deftypefunx int mpc_mul_si (mpc_t @var{rop}, mpc_t @var{op1}, long int @var{op2}, mpc_rnd_t @var{rnd})
 @deftypefunx int mpc_mul_fr (mpc_t @var{rop}, mpc_t @var{op1}, mpfr_t @var{op2}, mpc_rnd_t @var{rnd})
 Set @var{rop} to @var{op1} times @var{op2} rounded according to @var{rnd}.
+Note: for @code{mpc_mul}, in case @var{op1} and @var{op2} have the same value,
+use @code{mpc_sqr} for better efficiency.
 @end deftypefun
 
 @deftypefun int mpc_mul_i (mpc_t @var{rop}, mpc_t @var{op}, int @var{sgn}, mpc_rnd_t @var{rnd})
diff --git a/src/mul.c b/src/mul.c
index ead0087..2be9b8d 100644
--- a/src/mul.c
+++ b/src/mul.c
@@ -623,12 +623,6 @@ mpc_mul (mpc_ptr a, mpc_srcptr b, mpc_srcptr c, mpc_rnd_t rnd)
    if (mpfr_zero_p (mpc_realref (c)))
       return mul_imag (a, b, c, rnd);
 
-   /* Check if b==c and call mpc_sqr in this case, to make sure            */
-   /* mpc_mul(a,b,b) behaves exactly like mpc_sqr(a,b) concerning          */
-   /* internal overflows etc.                                              */
-   if (mpc_cmp (b, c) == 0)
-      return mpc_sqr (a, b, rnd);
-
    /* If the real and imaginary part of one argument have a very different */
    /* exponent, it is not reasonable to use Karatsuba multiplication.      */
    if (   SAFE_ABS (mpfr_exp_t,