From fa080de7afc95aa1c19a6e6fc0e0708ced2eadc4 Mon Sep 17 00:00:00 2001
From: Joseph Hunkeler <jhunkeler@gmail.com>
Date: Wed, 8 Jul 2015 20:46:52 -0400
Subject: Initial commit

---
 noao/astutil/pdm/pdmstats.x | 37 +++++++++++++++++++++++++++++++++++++
 1 file changed, 37 insertions(+)
 create mode 100644 noao/astutil/pdm/pdmstats.x

(limited to 'noao/astutil/pdm/pdmstats.x')

diff --git a/noao/astutil/pdm/pdmstats.x b/noao/astutil/pdm/pdmstats.x
new file mode 100644
index 00000000..aeabacaa
--- /dev/null
+++ b/noao/astutil/pdm/pdmstats.x
@@ -0,0 +1,37 @@
+include <mach.h>
+include <ctype.h>
+include <error.h>
+include "pdm.h"
+
+# PDM_STATISTICS -- Calculate the sum of squares and the variance of the data.
+
+procedure pdm_statistics (pdmp)
+
+pointer	pdmp			# pointer to PDM data structure
+
+int	npt, i, j
+double	var, sumx2, sum
+
+begin
+	npt = PDM_NPT(pdmp)
+
+	# Calculate the sum of squares and the variance of the data.
+	sumx2 = 0.0
+	sum = 0.0
+	j = 0
+
+	do i = 1, npt {
+	    if (PDM_INUSE(pdmp,i) == 1) {
+	        sumx2 = sumx2 + PDM_DY(pdmp,i)**2	    # Sum of squares.
+	        sum = sum + PDM_DY(pdmp,i)
+		j = j + 1
+	    }
+	}
+
+	if (j != 1)
+	    var = (sumx2 - sum**2/double(j))/double(j - 1)    # Variance.
+
+	# Put these two values in the data structure.
+	PDM_SUMSQ(pdmp) = sumx2
+	PDM_DVAR(pdmp) = var
+end
-- 
cgit