smooth FWHM

covert FWHM in voxel to in mm

load SPM.mat;

M = SPM.xVol.M;

VOX = sqrt(diag(M(1:3,1:3)'*M(1:3,1:3)))';

FWHM = SPM.xVol.FWHM;

FWHMmm= FWHM.\*VOX;

disp\(FWHMmm\)

when you specified a 5mm FWHM, the real one will be around 8 after caculation when you specified a 4mm FWHM, the real onw will be around 7.5 after caculation