PowerPoint Presentation - Time Series Analysis in AFNI

–81–

• See http://afni.nimh.nih.gov/doc/misc/3dDeconvolveSummer2004/

• Equation solver: Gaussian elimination to compute R matrix pseudo-inverse was replaced by SVD (like principal components)

H Advantage: smaller sensitivity to computational errors

H “Condition number” and “inverse error” values are printed at program startup, as measures of accuracy of pseudo-inverse

H Condition number < 1000 is good

H Inverse error < 1.0e-10 is good

• 3dDeconvolve_f program can be used to compute in single precision (7 decimal places) rather than double precision (16)

H For better speed, but with lower numerical accuracy

H Best to do at least one run both ways to check if results differ significantly (SVD solver should be safe)

Upgrades Since July 2004