Re: Mathematica and Lisp

*To*: mathgroup at smc.vnet.net*Subject*: [mg130056] Re: Mathematica and Lisp*From*: Murray Eisenberg <murray at math.umass.edu>*Date*: Thu, 7 Mar 2013 03:59:57 -0500 (EST)*Delivered-to*: l-mathgroup@mail-archive0.wolfram.com*Delivered-to*: l-mathgroup@wolfram.com*Delivered-to*: mathgroup-newout@smc.vnet.net*Delivered-to*: mathgroup-newsend@smc.vnet.net*References*: <kh4d3m$6vs$1@smc.vnet.net> <4997429.28227.1362539866570.JavaMail.root@m06> <001201ce1a1e$54a9fa90$fdfdefb0$@comcast.net> <20130306105512.571C563A5@smc.vnet.net>

The order of arguments of the 2-argument ArcTan seems to me merely an arbitrary choice. I cannot imagine why anybody would make the slightest fuss about it. Unless, that is, he's just determined to find things in Mathematica to carp about. On Mar 6, 2013, at 5:55 AM, Richard Fateman <fateman at eecs.berkeley.edu> wrote: > On 3/5/2013 7:54 PM, djmpark wrote: >> Reverse the order of what? ArcTan of one argument has only one argument and >> how can that be reversed? What has two arguments is the coordinate >> specification {x, y} and they are not reversed in ArcTan[x, y]. >> >> It is the one argument form ArcTan[y/x] that seems poorly designed and would >> probably only be used when one knows the quotient and not x and y - so there >> wouldn't be anything to reverse. >> >> >> From: Richard Fateman [mailto:fateman at cs.berkeley.edu] >> >> (simple example: why does Mathematica reverse the order of arguments to >> arctan of 2 args?) >> >> > ArcTan[x,y] in Mathematica gives the ArcTan[y/x] but in the correct > quadrant. > atan2 (y,x) in FORTRAN gives the arctangent of y/x). Note the order of > arguments. > in C++ > in Pascal > in Java > in Lisp (atan y x) > in PHP > in Python v 3.3.0 > in Ruby > > > > I was able to find just one programming language that agrees with the > order in Mathematica. > That is Microsoft's Excel. Now it could be that compatibility with Excel is > more important than compatibility with those other languages. Google > docs has to > use the same order as Excel, but I think it is generally recognized as being > compatible with an error. > Just sayin'. --- Murray Eisenberg murray at math.umass.edu Mathematics & Statistics Dept. Lederle Graduate Research Tower phone 413 549-1020 (H) University of Massachusetts 413 545-2838 (W) 710 North Pleasant Street fax 413 545-1801 Amherst, MA 01003-9305

**References**:**Re: Mathematica and Lisp***From:*Richard Fateman <fateman@eecs.berkeley.edu>