Re: Strange bug

*To*: mathgroup at smc.vnet.net*Subject*: [mg53288] Re: Strange bug*From*: Bill Rowe <readnewsciv at earthlink.net>*Date*: Tue, 4 Jan 2005 03:13:49 -0500 (EST)*Sender*: owner-wri-mathgroup at wolfram.com

On 1/3/05 at 4:29 AM, stevebg at adelphia.net (Steve Gray) wrote: >I have procedural function "ordermat." It works ok if the >next-to-last (useless) line is there but if I remove that one line, >I get error messages due to the last line, at execution time: >Set::write: Tag Times in Null\{0, 0, 0, 0, 0, 0, 0, 0, 0, 0, >\[LeftSkeleton]1\ \[RightSkeleton]} is Protected. >("intersect" returns a small integer and computes "tafr.") >I've seen bugs like this before. I'm using 5.0.1.0 with Windows. >Any clues? Thanks in advance. >ordermat[gon_] := Module[{row, rx, cx}, > gonl = Length[gon]; > matx = Table[0, {i, 1, gonl}, {j, 1, gonl}]; > gona = Join[gon, gon]; > For [ rx = 1, rx <= gonl, rx++, > row = Table[0, {2*gonl}]; > row[[rx]] = 1; > row[[rx + 1]] = 2; > ab = gona[[rx]]; > ae = gona[[rx + 1]]; > For [ cx = 1, cx <= gonl - 3, cx++, > bb = gona[[cx + rx + 1]]; > be = gona[[cx + rx + 2]]; > int = intersect[ab, ae, bb, be]; > If [ int == 3, row[[cx + rx + 1]] = tafr + 1]; > ] > rx; (* Error unless some expression is here.?? *) > matx[[rx]] = Table[Max[row[[i]], row[[i + gonl]]], {i, gonl}]; > ] > ] As near as I can tell, this code simply creates a square matrix whose first row is {1,2,0,0...} and every subsequent row is rotated one position right. If so, the following code does the same thing much more efficiently ordermat[n_]:= Module[{row = PadRight[{1, 2}, n]}, Join[{row}, RotateRight[row, #1]&/@Range[n-1]]] and matx = ordermat[Length@gon] produces the same result as your code. -- To reply via email subtract one hundred and four