From bb6f2daae14b2b8a09ced0ccc7e8147c7c2c01d6 Mon Sep 17 00:00:00 2001
From: Paolo Veglio <paolo.veglio@ssec.wisc.edu>
Date: Thu, 7 Mar 2024 10:26:52 +0000
Subject: [PATCH] fixed visible reflectance test
---
mvcm/c_tools/conf_test.c | 127 +++++++++++++++++++++++++++++++++++++++
1 file changed, 127 insertions(+)
create mode 100644 mvcm/c_tools/conf_test.c
diff --git a/mvcm/c_tools/conf_test.c b/mvcm/c_tools/conf_test.c
new file mode 100644
index 0000000..1703369
--- /dev/null
+++ b/mvcm/c_tools/conf_test.c
@@ -0,0 +1,127 @@
+/**********************************************************************
+Description:
+
+ Float function conf_test.c
+
+ Computes clear sky confidence value for an individual spectral test.
+ Input single threshold value ('midpt') with associated confidence
+ limits ('locut', 'hicut'). "Low" and "high" cutoffs refer to low
+ or high confidence ends of an interval and not necessarily to
+ absolute values. Routine calculates the confidence based on an "S"
+ function. One may change the shape of the function by changing
+ 'power' and/or 'midpt'.
+
+Input arguments:
+ float val parameter to be tested (BT, BTD, etc.)
+ float locut low confidence cutoff (< locut = confidence of 0.0)
+ float hicut high confidence cutoff (> hicut = confidence of 1.0)
+ float power S function power (1.0 = linear funtion)
+ float midpt midpoint of S function (= confidence of 0.5)
+
+Output arguments:
+ none
+
+ float confidence output clear sky confidence (0.0 - 1.0)
+ (returned through function call)
+
+Revision History:
+ 05/2007 R. Frey Converted to C
+ 10/2012 R. Frey Included in MVCCM software
+
+Calls:
+ none
+
+***********************************************************************/
+
+/* Includes */
+
+#include <stdio.h>
+#include <math.h>
+
+
+float conf_test(float val, float locut, float hicut, float power,
+ float midpt)
+
+
+{
+
+/* Declarations */
+
+ extern float powf(float, float);
+
+ int flipped;
+
+ float confidence;
+ float coeff;
+ float alpha;
+ float gamma;
+ float beta;
+ float range;
+ float s1;
+ float c;
+
+/* Initializations */
+
+ coeff = powf(2.0, (power - 1.0));
+
+/* Find if high confidence cutoff is the numerically lowest or highest
+ value. */
+ if(hicut > locut) {
+ gamma = hicut;
+ alpha = locut;
+ flipped = 0;
+ } else {
+ gamma = locut;
+ alpha = hicut;
+ flipped = 1;
+ }
+
+ beta = midpt;
+
+/* If value ('val') lies outside function range, confidence is either
+ 0.0 or 1.0. */
+
+ if(flipped == 0 && val > gamma) {
+ c = 1.0; }
+
+ else if(flipped == 0 && val < alpha) {
+ c = 0.0; }
+
+ else if(flipped == 1 && val > gamma) {
+ c = 0.0; }
+
+ else if(flipped == 1 && val < alpha) {
+ c = 1.0; }
+
+ else {
+
+/* Otherwise, value ('val') is within the function range and the
+ confidence is between 0.0 and 1.0. */
+
+ if(val <= beta) {
+
+ range = 2.0 * (beta - alpha);
+ s1 = (val - alpha) / range;
+ if(flipped == 0) c = coeff * powf(s1, power);
+ if(flipped == 1) c = 1.0 - (coeff * powf(s1, power)); }
+
+ else {
+
+ range = 2.0 * (beta - gamma);
+ s1 = (val - gamma) / range;
+ if(flipped == 0) c = 1.0 - (coeff * powf(s1, power));
+ if(flipped) c = coeff * powf(s1, power);
+
+ }
+
+ }
+
+/* Force confidence values to be between 0 and 1. */
+ if(c > 1.0) c = 1.0;
+ if(c < 0.0) c = 0.0;
+
+ confidence = c;
+
+ return confidence;
+
+}
--
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