I have updated QuickSAND (http://jaw.fmnh.org/ND.html), a freeware package
for the automated Quick Smoothing And Numerical Differentiation. The
software if for PowerMacs and clones only.

Changes include:
-one new routine (Butterworth filter with automatic finding of optimal
cutoff frequency)
-interface enhancements, including (1) the addition of a results window
that outputs important coefficients (cutoff frequencies, etc.), (2)
unlimited sample size
-3 bug fixes (instability of LAMBDA, 1st derivative of LAMBDA, and location
of saved file):

Routines include:
1. Woltring implementation of Generalized Cross-Validatory Spline Smoothing
and Differentiation (Woltring 1986).
2. Kasarov-Pantos approximation of the optimal Wiener filter (Gazzani 1994).
3. LAMBDA (Linear-phase Autoregressive Model-Based Derivative Assessment
Algorithm) (D'Amico & Ferrigno 1990, 1992). A filter based on the Power
density spectrum.
4. Piecewise polynomial of any odd-piecelength and polynomial order up to
20 (Lanshammar 1982).
5. 4th central difference smoothing and differentiation (Lanczos 1957).
6. Optimal Bidirectional 2nd order Butterworth digital Filter (Winter 1990)
using autocorrelation analyis (Cappello et al. 1996).

Cappello A, La Palombara PF, Leardini A. 1996. Optimization and smoothing
techniques in movement analysis. International Journal of Bio-Medical
Computing 41: 137-151.

D'Amico M, Ferrigno G. 1990. Technique for the evaluation of derivatives
from noisy biomechanical displacement data using a model-based
bandwidth-selection procedure. Medical & Biological Engineering & Computing
28: 407-415.

D'Amico M, Ferrigno G. 1992. Comparison between the more recent techniques
for smoothing and derivative assessment in biomechanics. Medical &
Biological Engineering & Computing 30: 193-204.

Gazzani F. 1994. Comparative assessment of some algorithms for
differentiating noisy biomechanical data. International Journal of
Bio-Medical Computing 37: 57-76.

Lanczos C. 1957. Applied Analysis. London: Isaac Pitman & Sons. Reprinted
by Dover, 1988.

Lanshammar H. 1982. On practical evaluation of differentiation techniques
for human gait analysis. Journal of Biomechanics 15: 99-105.

Winter DA. 1990. Biomechanics and Motor Control of Human Movement. New
York: John Wiley & Sons.

Woltring HJ. 1986. A Fortran package for generalized, cross-validatory
spline smoothing and differentiation. Advances in Engineering Software 8:


Jeff Walker

Jeff Walker
Dept. of Zoology
Field Museum of Natural History
Roosevelt Rd. at Lake Shore Dr.
Chicago, IL 60605, USA
phone: 312-922-9410 x537 fax: 312-427-7269
email: walker@fmppr.fmnh.org
web: http://jaw.fmnh.org/Home.html

"I like practical applications in mathematics, rather than speculating
about the first ten to the minus something seconds of the universe.
Cosmology seems to be almost too close to theology to be interesting.
To me, it is not quite science, but more like creation myth."

- Sir James Lighthill