iFit/sign

 b = sign(s) : sign of iData object

   @iData/sign function to return the sign of data sets
   This function computes the sign of the object 's', i.e
   -1 for negative values, 0 for null, and +1 for positive values.

 input:  s: object or array (iData)
 output: b: object or array (iData)
 ex:     b=sign(a);

 Version: Aug. 22, 2017
 See also iData, iData/sign, iData/isreal, iData/isfinite, iData/isnan,
          iData/isinf, iData/isfloat, iData/isinterger,
          iData/isnumeric, iData/islogical, iData/isscalar,
          iData/isvector, iData/issparse