[R] heatmaps depending on RAM?

[Thomas Zander]

I have the following problem. Analysing affymetrix data I calculated 
euclidean distances between samples and visualized the results in a 
heatmap. Prior data were vsn normalized.

heatmap(as.matrix(dist(t(exprs(TGF_eset.vsn[(tvlist),])))), col=colourRamp)

Depending on the memory  I assign to R (512MB, 1024MB, 1536MB) I get 
slightly different results. Exactly the same scripts were used. Although 
main results remain in the detail I have differences. Is there any 
explanation for these results?

thanks for the help


Thomas Zander

Dr. Thomas Zander
MTBTI, HS16UG
Dept. of Internal Medicine I
Universitätsklinik Köln
Joseph-Stelzmannstr. 9
D-50924 Köln
Germany
Tel.: +49-221-4784447/ 4785413
Fax: +49-221-4783647
Thomas.Zander at uk-koeln.de