Re: casting

[John W. Eaton]

On 13-Mar-2007, Søren Hauberg wrote:

| Just a few stupid questions :-)
| Is feval really so slow that you switch-case is faster?

No, feval should be is approximately the same as calling a function.
But a series of switch cases is probably slightly faster than a series
of calls to strcmp.  You are right that using strcmp with a cell array
is probably faster than a series of switch cases.  I just forgot that
strcmp could be used this way.  So I changed the function to

  function retval = cast (val, typ)

    if (nargin == 2)
      if (ischar (typ))
        if (any (strcmp (typ, {"int8"; "uint8"; "int16"; "uint16";
                               "int32"; "uint32"; "int64"; "uint64";
                               "double"; "single"})))
          retval = feval (typ, val);
        else
          error ("cast: type name `%s' is not a built-in type", typ);
        endif
      else
        error ("cast: expecting type name as second argument");
      endif
    else
      print_usage ();
    endif

  endfunction


| Also, I that you handle the "single" type in your code. Does octave 
| support "single" now?

Not really, but there is a single function that converts to double.
It's not completely correct, but doing that allows some code that
requires single to run.

Thanks,

jwe