unifinv and colleagues with single arguments

[John W. Eaton]

On 13-Mar-2009, Francesco Potorti` wrote:

| unifinv (single(0.5), 1, 3) returns a double in 3.1.54.
| 
| Is this anticipated and correct?
| 
| Maybe it should return a single if either of its arguments is single.

Yes, it should return a single value.  Looking at unifinv, I see:

  function inv = unifinv (x, a, b)

    if (nargin != 1 && nargin != 3)
      print_usage ();
    endif

    if (nargin == 1)
      a = 0;
      b = 1;
    endif

    if (!isscalar (a) || !isscalar(b))
      [retval, x, a, b] = common_size (x, a, b);
      if (retval > 0)
	error ("uniform_cdf: x, a and b must be of common size or scalar");
      endif
    endif

    sz = size (x);
    inv = zeros (sz);

Instead, we need to initialize the return value to single if any of
the arguments are single.  Something like:

  if (isa (x, "single") || isa (a, "single") || isa (b, "single"))
    inv = zeros (sz, "single");
  else
    inv = zeros (sz, "double");
  endif

This kind of change will likely be needed in more than just
unifinv.m.  Would someone like to take a look at all the distribution
functions and contribute a changeset?

| Is there an easy way of determining if a returned value is single?  The
| only way that I have found is to assign it to a variable and use whos on it.

Try class (x).

jwe