On Mon, 27 Apr 2009 17:04:17 -0400, Michael S. Gilbert wrote: > I had mentioned recently some interest in using fractions in the numpy > polynomial class. Suprisingly, it actually works for the most part out > of the box, which is great. However, there are some minor issues. For > example: > > >>>> numpy.poly1d( [ fractions.Fraction(1,2) , fractions.Fraction(1,8) ] > >>>> )/fractions.Fraction(3,4) > > fails, so I have to move the division into the inner list, which leads > to a lot of duplicate typing and general messiness: > > >>>> numpy.poly1d( [ fractions.Fraction(1,2)/fractions.Fraction(3,4) , > >>>> fractions.Fraction(1,8)/fractions.Fraction(3,4) ] ) > > Another item of general interest for numpy is that there is no simple > way to allocate memory for fraction array. > > >>>> def zeros( nsamples ): > >>>> list = [] > >>>> for n in range( nsamples ): > >>>> list.append( fractions.Fraction( 0 ) ) > >>>> return numpy.array( list ) > > is a solution, but it would be nice to have this built-in, e.g.: > > >>>> numpy.zeros( n , dtype=numpy.fraction ) > > Perhaps developing a fraction dtype would solve the above poly1d issue > as well? Anyway, just some thoughts to ponder.
It also seems that numpy's basic math operations do not work with fractions: >>> math.sin(fractions.Fraction(1,2)) 0.47942553860420301 >>> numpy.sin(fractions.Fraction(1,2)) Traceback (most recent call last): File "<stdin>", line 1, in <module> AttributeError: sin >>> numpy.exp(fractions.Fraction(1,2)) Traceback (most recent call last): File "<stdin>", line 1, in <module> AttributeError: exp Mike _______________________________________________ Numpy-discussion mailing list Numpy-discussion@scipy.org http://mail.scipy.org/mailman/listinfo/numpy-discussion
