Changeset 40060 for trunk

Timestamp:

Jun 1, 2017, 4:23:59 PM (9 years ago)

Author:

eugene

Message:

add outline for IRLS discussion

File:

• trunk/doc/release.2015/ps1.calibration/calibration.tex (modified) (1 diff)

trunk/doc/release.2015/ps1.calibration/calibration.tex

@@ -1603 +1603 @@
 \subsubsection{Iteratively Reweighted Least Squares Fitting}
 
+\begin{verbatim}
+subsection outline
+* motivation (high outlier rate -- quantify?)
+* data prep:
+  * all R,D values are projected to a locally-linear coordinate system
+  * the time is modified to refer to the mean epoch (why?)
+  * parallax factors are calculated for each epoch
+* data: X + dX, Y + dY
+* sequence
+  * ordinary least-squares fit
+  * calculate deviations from the fit
+  * calculate a weight-factor based on (Rx / sigmax)
+  * multiply standard weight by weight-factor
+  * fit using modified weights
+  * check for convergence:
+    * if (B_i - B^\prime_i) > Tol * |B_i|
+    * if (B_i - B^\prime_i) > Tol_value
+  * if not converged, repeat 
+  * once done, calculate the weight-factors again
+    * points with weight-factors < THRESHOLD * ave weight factor : mask
+    * calculate chi-square value using unmasked points
+  * run bootstrap re-sampling (with unmasked points) to determine the errors
+\end{verbatim}
+
 \subsubsection{Seletion of Measurements}