Re: Arrays and Matrix Algebra
Just wanted to confirm the correct way to set up arrays to be able to do matrix math. If I have an array named X, does MetaCard treat x[3,4] as the fourth element in the third row of X and x[8,2] as the second element in the eigth row? Regards, Greg Greg, I don't really follow this list much anymore (or use Metacard much either), but you might find my library of scripts useful...I remember writing some for matrix math, etc. You can find it at: http://www.phbeads.com/pub/metacard/ HTH, Dave ___ metacard mailing list [EMAIL PROTECTED] http://lists.runrev.com/mailman/listinfo/metacard
Re: Julian dates
Anyone got an xTalk algorithm for converting between standard and Julian dates they can share? Richard, check out the following functions from the stack script of my jonesLib stack: function dayNum function julianDate function gregorianDate The functions dayNum and julianDate offer different versions of a Julian day. Get the stack from: http://www.phbeads.com/pub/metacard/ HTH, Dave http://www.phbeads.com Archives: http://www.mail-archive.com/metacard@lists.runrev.com/ Info: http://www.xworlds.com/metacard/mailinglist.htm Please send bug reports to [EMAIL PROTECTED], not this list.
Re:built-in matrix functions (was: file sharing (was: Misc. array, ...))
Scott Raney [EMAIL PROTECTED]wrote: I second the motion: we are already planning to add some features in this area for the next release and a list of the most useful matrix operations to have built in would be very handy for planning purposes. This is what I'd like to see for matrices (for matrix, I assume you are referring to 2 dimensional associative array, or will you be creating a new matrix object? 1) a quick method of creating a matrix in memory out of a comma-separated-values (or whatever token the user wants to use) from a field, variable, or data file 2) a quick method of exporting the values from a matrix to a token-separated-values field, variable, or data file - both of these should allow the user to specify whether or not the first row of data contains the column labels and the first items of each row contain the row labels...if labels are specified they should be used in the associative array as myArray[r,c] otherwise some standard value for [r,c] should be used. 3) basic matrix algebra: matrix addition, subtraction, multiplication, division...division can be accompished by finding the inverse of the divisor matrix and then using it in matrix multiplication 4) matrix transposition 5) matrix transformation via square root, fourth root, log (y + 1), natural log, and whatever else the rest of the MetaCard community find useful --- these a feel are probably the MOST important, other things I'd like and could readily use are: - 6) matrix sorting and ranking (column-wise, row-wise, and array-wise); my matrix ranking routines are TOO slow and have been major bottlenecks in some of my analyses. 7) normalize a matrix 8) triangularize a matrix, and the inverse: make it symmetrical My jonesLib.mc stack has handlers for all of this if an algorithm or example is needed, however, I'd really like to see these optimized in the MetaCard engine to handle LARGE data sets and allow FAST responses. I've been working with some 2 dimensional arrays that were 300 rows by 300 columns (some multivariate dissimilarity data), and could usually get the job done, but often some of my handlers took a LONG time. Dave Jones Archives: http://www.mail-archive.com/metacard@lists.runrev.com/ Info: http://www.xworlds.com/metacard/mailinglist.htm Please send bug reports to [EMAIL PROTECTED], not this list.
Re: matrix algebra and stats routines
I've used MetaCard rather extensively during the last 1.5 yrs to process and analyze data for my dissertation (and to feed my 3d graphics hobby addiction). I've avoided matLab entirely and opted for MetaCard because I feel it is 'generically more useful'. In the process I've written many handlers and functions to help with my multivariate analysis, many of which rely on using 2d array objects. Its nice to see other people doing this and I'd definitely like to see us pool our resouces so we don't have to reinvent the wheel. Trading scripts and stacks would be nice BUT incorporating our routines into the MC engine itself would definitely be ideal, especially for speed when processing large arrays of data. I'd appreciate receiving any stats libraries you might have and I'll try to put mine up on the Web this week as I'm sure something in there will be of use to someone. I'm especially proud of my "combinatorial" script which finds all possible subsets of a set of "objects". It took me a week to figure this one out and I believe I discovered a NEW algorithm in the process (I think saturating my brain on "Pascal's Triangle" helped prime my thought processes). Also, I think I might have a HyperCard stack somewhere that has a solution for SVD, but I'm sure it won't involve MetaCard arrays. One thing I'd love to see in the MC engine is a QUICK way to get the contents of a large array OUT and put them in a text field. `'*:-.,_,.-:*'``'*:-.,_,.-:*'``'*:-.,_,.-:*'``'*:-., Dave Jones Dept. of Marine Biology Fisheries Univ. of Miami - RSMAS 4600 Rickenbacker CSWY Miami, FL 33149 Tel. 305-361-4246 Fax. 305-361-4600 http://www.rsmas.miami.edu/ Archives: http://www.mail-archive.com/metacard@lists.runrev.com/ Info: http://www.xworlds.com/metacard/mailinglist.htm Please send bug reports to [EMAIL PROTECTED], not this list.
