*To*: mathgroup@smc.vnet.net*Subject*: [mg12020] Speeding up ReadList[]?*From*: sidles@u.washington.edu (John Sidles)*Date*: Fri, 17 Apr 1998 03:40:55 -0400*Organization*: University of Washington, Seattle

I use Mathematica to process Excel spreadsheets containing large arrays ({500,500}) of ASCII-coded floats. To read in the lists, I use the Mathematica function ReadList[stream, Number, RecordLists->True] Everything works fine, except that as each new array, is read and processed, ReadList[] gets slower and s l o w e r and s...l...o...w...e...r. The first ReadList[] takes only 40 seconds, while the second ReadList[] can take 400 seconds or longer, and I don't even know how long the third ReadList[] takes. Each file is processed independently, and no large arrays are retained in memory (they are stored as local variables inside Module[] blocks). VIrtual memory is not used, and both the Kernel and the Notebook retain plenty of unallocated memory. Each file does generate a large Graphics[] object, but surprisingly, Mathematica does not slow down while computing each graphic. Thus, ReadList[] is the only function evidencing a slowdown. Neither the MathSource nor the FAQ seem to address this problem. Has anyone else run into this slowdown, and how can it be avoided? Thanks ... JAS

**Follow-Ups**:**Re: Speeding up ReadList[]?***From:*Sean Ross <seanross@worldnet.att.net>