Re: question (for Mathematica 6!)

*To*: mathgroup at smc.vnet.net*Subject*: [mg75572] Re: [mg75519] question (for Mathematica 6!)*From*: Murray Eisenberg <murray at math.umass.edu>*Date*: Sat, 5 May 2007 06:07:20 -0400 (EDT)*Organization*: Mathematics & Statistics, Univ. of Mass./Amherst*References*: <200705040809.EAA04730@smc.vnet.net>*Reply-to*: murray at math.umass.edu

One difference is that HeavisideTheta[0] is undefined, whereas UnitStep[0] is 1. The docs say this: see the descriptions say this implicitly at the tops of the functions' "home pages"; the "Possible Issues" section on HeavisideTheta explicitly says "HeavisideTheta stays unevaluated for vanishing argument." Another is that, as the docs say, Piecewise Expand does not operate upon HeavisideTheta because "it is a distribution and not a piecewise-defined function." That is, PiecewiseExpand[HeavisideTheta[a]] just returns HeavisideTheta. However, PiecewiseExpand[UnitStep[x]] returns, in InputForm, Piecewise[{{1,x>=0}},0]. dimitris wrote: > I don't have a copy of Mathematica 6 but having spent much time > reading the online documentation (not only because of curiosity!) I > have one question... > > Can somebody explain me the introduction of the HeavisideTheta > function > > http://reference.wolfram.com/mathematica/ref/HeavisideTheta.html > > in version 6? > > Note that the UnitStep function is still here > > http://reference.wolfram.com/mathematica/ref/UnitStep.html > > Dimitris > > -- Murray Eisenberg murray at math.umass.edu Mathematics & Statistics Dept. Lederle Graduate Research Tower phone 413 549-1020 (H) University of Massachusetts 413 545-2859 (W) 710 North Pleasant Street fax 413 545-1801 Amherst, MA 01003-9305

**References**:**question (for Mathematica 6!)***From:*dimitris <dimmechan@yahoo.com>