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In weight calculation use unweighted variance from last regression

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This fixes a positive feedback where weights could reach inf.
Also change the SD_TO_DIST_RATIO constant to get close to the original
response.
This commit is contained in:
Miroslav Lichvar
2011-04-13 18:43:25 +02:00
parent 2a0c35646c
commit 165e6805ab
3 changed files with 18 additions and 9 deletions
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12
regress.c
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@@ -232,6 +232,7 @@ RGR_FindBestRegression
double *b0, /* estimated y axis intercept */
double *b1, /* estimated slope */
double *s2, /* estimated variance of data points */
double *us2, /* estimated unweighted variance of data points */
double *sb0, /* estimated standard deviation of
intercept */
@@ -250,7 +251,7 @@ RGR_FindBestRegression
{
double P, Q, U, V, W; /* total */
double resid[MAX_POINTS * REGRESS_RUNS_RATIO];
double ss;
double ss, uss;
double a, b, u, ui, aa;
int start, resid_start, nruns, npoints;
@@ -310,17 +311,20 @@ RGR_FindBestRegression
*b1 = b;
*b0 = a;
ss = 0.0;
ss = uss = 0.0;
for (i=start; i<n; i++) {
ss += resid[i - resid_start]*resid[i - resid_start] / w[i];
uss += resid[i - resid_start]*resid[i - resid_start];
}
npoints = n - start;
ss /= (double)(npoints - 2);
ss /= npoints - 2;
uss /= npoints - 2;
*sb1 = sqrt(ss / V);
aa = u * (*sb1);
*sb0 = sqrt((ss / W) + (aa * aa));
*s2 = ss * (double) npoints / W;
*s2 = ss * npoints / W;
*us2 = uss;
*new_start = start;
*dof = npoints - 2;