some questions about the complex datatype

[Peter Jay Salzman]

hi there,

the libc page mentioned that questions can be forwarded to this list.
if there's a better place to ask questions, please advise me where to
go.  also, is there a way to subscribe to this list?


a couple of questions about the complex datatype:

how can i get gdb to print out the value of a long double complex?  i
tried everything that was obvious to me.  for a long double complex a:

   (gdb) ptype a
   type = complex long double
   (gdb) p a
   $2 = Invalid C/C++ type code 20 in symbol table.
   (gdb) p creall(a)
   $3 = 1
   (gdb) p cimagl(a)
   $4 = 1
   (gdb) printf "%Le, %Le", a
   Wrong number of arguments for specified format-string
   (gdb) printf "%Le", a
   Value can't be converted to integer.

at this point, i'm stumped.  what's the magic here?


also, if Psi[i] is a long double complex, i'm a little confused how to
print |Psi[i]|^2.  the obvious thing from a math standpoint would be 

   fprintf(fp, "%Le", conj(Psi[i]) * Psi[i]);

which doesn't work.  gcc complains that %Le is for long doubles and
conj(Psi[i]) * Psi[i]) is long double complex.   the abs() function
takes doubles.  and the info pages don't mention anything about a
cabsl() function (which would be really nice).

how can i print the real number conj(z) * z to a file?   do i really
have to resort to something really horrible like:

   fprintf(fp, "%Le", sqrtl( creal(Psi[i]) * Psi[i]) creal(Psi[i]) * Psi[i])
      + cimagl(Psi[i]) * Psi[i]) cimagl(Psi[i]) * Psi[i]) ) );

(i'm staying away from pow() for speed considerations).

thanks!   :)

pete

ps - sorry if this is gcc related and not libc related.  it's my
understanding that these questions are library related, not compiler
related.  but the truth is i'm a physicist, not a CS major...


-- 
The mathematics [of physics] has become ever more abstract, rather than more
complicated.  The mind of God appears to be abstract but not complicated.
He also appears to like group theory.  --  Tony Zee's `Fearful Symmetry'

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