Hi,

I'm trying to combine 2 sets of clusters, but I'm experiencing problems manipulating them with 3dcalc.
One of the 2 sets (clustCorr+orig) has 9 clusters, the other (clustSpaz+orig) 60. I would like to potentially get 540 (9*60) distinct clusters.
I tried to get this muliplying the values of each voxel in the first set of cluster (interger values ranging from 0 to 9) times 100, so the new indexes of the voxels of the clusters should be 0, 100, 200, ..., 900.

3dcalc -a clustCorr+orig -expr "a*100" -prefix clustCorr100

The next step was to add, voxel by voxel, the values of the new obtained dataset with the ones in the 60 clusters' dataset:

3dcalc -a clustSpaz+orig -b clustCorr100+orig -expr "a+b" -prefix clustSpaz+Corr100

Well, I experienced two problems:

1. in the first step (multiplication) I got unspected decimal values (e.g.: 98.7982, 116.0981).

2. in the second step (summation) I got the same result adding two different pairs of numbers (e.g.: 201.1765 + 8 = 209.7256 , but also 201.1765 + 10 = 209.7256).

What's going on? Am I using 3dcal in an improper way? Or am I manipulating datasets of a "wrong type"?

Any suggestion?

Thanks,

Davide