RE: newbie Comment question

*To*: mathgroup at smc.vnet.net*Subject*: [mg47028] RE: [mg47018] newbie Comment question*From*: "David Park" <djmp at earthlink.net>*Date*: Mon, 22 Mar 2004 05:18:40 -0500 (EST)*Sender*: owner-wri-mathgroup at wolfram.com

Janos, Comments in Mathematica are inserted using (* .... *). So you could use... line1; (* line2; *) line3; However, in my humble opinion, comments in Mathematica are poorly implemented and, except for commenting out, are almost totally useless. In package code they cause parsing errors. If you convert an Input Cell from on Form to another, say from StandardForm to InputForm, the comments are thrown away. Weaving some comments into code is a very useful and proper programming practice. Text cell comments are in no way a substitute for this. Comments should be considered as part of the proper syntax of all Input cells. They should not be thrown out when converting between various input Forms. The parser should handle comments simply by skipping over them. This is a long standing incorrectly implemented feature of Mathematica. I would like to point out another, this time good feature of Mathematica that many are unaware of. It is very convenient to do a calculation with multiple input lines in one cell. It is also easy to add comments in the form of Print statement so that you have commented output. You can use the % and %% expressions quite safely within a single cell. You can use statement1; and still refer to its output as %. Here is a simple example of commented output. Print["Starting equation"] a x + b == c Print["Subtract b from both sides"] # - b & /@ %% Print["Divide by a"] #/a & /@ %% If you close up the Input cell, using Alt-C-R-C, your notebook will have just the commented output. This is very convenient for displaying derivations in Mathematica. David Park djmp at earthlink.net http://home.earthlink.net/~djmp/ From: János [mailto:janos.lobb at yale.edu] To: mathgroup at smc.vnet.net I have lines and lines of codes. Like line1; line2; line3; I would like to comment out line2 temporary. How do I do it ? I tried to look hard in the Book last night, but found nothing. Related question. If I do not want to insert a text cell to explain what a line does, how can I add comments to the lines ? In other languages /*....*/ or // would work, but not here. I do not know yet how to add text cells, but would like to comment the code I do. Thanks ahead, János ------------------------------------------------- clear perl code is better than unclear awk code; but NOTHING comes close to unclear perl code http://www.faqs.org/faqs/computer-lang/awk/faq/