Re: [OctDev] Can we implement isinteger this way?

[William P. Y. H <wil...@ya...>]

--- Andy Adler <ad...@nc...> wrote:
> 
> Are you happy with the way this function will handle large
> exponents where the interger part is lost? For example
> 
> octave:6> isinteger(1e10/3)
> ans = 0
> octave:7> isinteger(1e20/3)
> ans = 1
> 
> Andy
> 

Well... I'm not. But I can't think of a better way...
Btw, actually 1e20/3 should be treated as an integer anyway (or a floating
point with zero behind the decimal point) because Octave can't handle it. I
meant to use this function to check for integer count arguments passed to
functions, and I think most people would do the same thing, so...

In the meantime, I've modified it a bit (thanks Paul):

function retval = isinteger(A)
## -*- texinfo -*-
## @deftypefn {Function File} {} isinteger (@var{A})
## Return 1 if @var{A} is an integer array.  Otherwise, return 0.
## @end deftypefn
##
## @seealso{isa, isnumeric, isfloat}

if (nargin ~= 1)
  usage("isinteger(A)");
end

retval = ismatrix(A) && all((round(A) == A)(:));

And now I also have an isfloat function:

function retval = isfloat(A)
## -*- texinfo -*-
## @deftypefn {Function File} {} isfloat (@var{A})
## Return 1 if @var{A} is a floating point array.  Otherwise, return 0.
## @end deftypefn
##
## @seealso{isa, isinteger, isnumeric}

if (nargin ~= 1)
  usage("isfloat(A)");
end

retval = ismatrix(A) && ~all((round(A) == A)(:));


William Poetra Yoga Hadisoeseno


		
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