fix statistics of new_sv_measure, and reduce number of steps in

check_gain_chan_x

diff --git a/comedi_calibrate/comedi_calibrate.c b/comedi_calibrate/comedi_calibrate.c
index 75c396d57b6bac8963b28bd283b83e9dd02434ae..6209c031db738602da2bb3f7ce38274689249259 100644 (file)
--- a/comedi_calibrate/comedi_calibrate.c
+++ b/comedi_calibrate/comedi_calibrate.c
@@ -967,7 +967,7 @@ double check_gain_chan_x( calibration_setup_t *setup, linear_fit_t *l,unsigned i
        n = setup->caldacs[cdac].maxdata+1;
        memset(l,0,sizeof(*l));
 
-       step=n/256;
+       step=n/16;
        if(step<1)step=1;
        l->n=0;
 
@@ -1005,7 +1005,7 @@ double check_gain_chan_x( calibration_setup_t *setup, linear_fit_t *l,unsigned i
 
        update_caldac( setup, cdac, orig );
 
-       l->yerr=sum_err/sum_err_count;
+       l->yerr=sum_err/sqrt(sum_err_count);
        l->dx=step;
        l->x0=0;
 
@@ -1076,7 +1076,7 @@ double check_gain_chan_fine( calibration_setup_t *setup, linear_fit_t *l,unsigne
 
        update_caldac( setup, cdac, orig );
 
-       l->yerr=sum_err/sum_err_count;
+       l->yerr=sum_err/sqrt(sum_err_count);
        l->dx=1;
        l->x0=orig-fine_size;
 
@@ -1294,7 +1294,7 @@ int new_sv_measure( comedi_t *dev, new_sv_t *sv)
        lsampl_t *data;
        int n,i,ret;
 
-       double a,x,s,s2;
+       double x,s,s2;
 
        n=1<<sv->order;
 
@@ -1320,15 +1320,16 @@ int new_sv_measure( comedi_t *dev, new_sv_t *sv)
 
        s=0;
        s2=0;
-       a=comedi_to_phys(data[0],sv->rng,sv->maxdata);
-       for(i=0;i<n;i++){
-               x=comedi_to_phys(data[i],sv->rng,sv->maxdata);
-               s+=x-a;
-               s2+=(x-a)*(x-a);
+       for(i = 0; i < n; i++){
+               x = comedi_to_phys(data[i], sv->rng, sv->maxdata);
+               s += x;
+               s2 += x * x;
        }
-       sv->average=a+s/n;
-       sv->stddev=sqrt(n*s2-s*s)/n;
-       sv->error=sv->stddev/sqrt(n);
+       s /= n;
+       s2 /= n;
+       sv->average=s;
+       sv->stddev=sqrt( ( ( n + 1 ) / n ) * ( s2 - s * s ) );
+       sv->error=sv->stddev / sqrt( n );
 
        ret=n;
 
@@ -1342,7 +1343,7 @@ int new_sv_measure_order( comedi_t *dev, new_sv_t *sv,int order)
 {
        lsampl_t *data;
        int n,i,ret;
-       double a,x,s,s2;
+       double x,s,s2;
 
        n=1<<order;
 
@@ -1361,15 +1362,16 @@ int new_sv_measure_order( comedi_t *dev, new_sv_t *sv,int order)
 
        s=0;
        s2=0;
-       a=comedi_to_phys(data[0],sv->rng,sv->maxdata);
-       for(i=0;i<n;i++){
-               x=comedi_to_phys(data[i],sv->rng,sv->maxdata);
-               s+=x-a;
-               s2+=(x-a)*(x-a);
+       for(i = 0; i < n; i++){
+               x = comedi_to_phys(data[i], sv->rng, sv->maxdata);
+               s += x;
+               s2 += x * x;
        }
-       sv->average=a+s/n;
-       sv->stddev=sqrt(n*s2-s*s)/n;
-       sv->error=sv->stddev/sqrt(n);
+       s /= n;
+       s2 /= n;
+       sv->average = s;
+       sv->stddev=sqrt( ( ( n + 1 ) / n ) * ( s2 - s * s ) );
+       sv->error=sv->stddev / sqrt( n );
 
        ret=n;