dive4elements/river: flys-artifacts/src/main/java/de/intevation/flys/artifacts/model/DischargeTables.java comparison

Discharge table: we need a getQForW() and not a getWForQ(). flys-artifacts/trunk@1732 c6561f87-3c4e-4783-a992-168aeb5c3f6f

author	Sascha L. Teichmann <sascha.teichmann@intevation.de>
date	Tue, 19 Apr 2011 17:37:21 +0000
parents	67b3f54188aa
children	7f13ed751277

comparison

equal deleted inserted replaced

-:67b3f54188aa
+:b7c8df643dc4
 }
 return values;
 }
-public static boolean getWForQ(
+public static double getQForW(
 double [][] values,
-double      q,
+double      w,
 double []   result
 ) {
-int index = Arrays.binarySearch(values[1], q);
+int index = Arrays.binarySearch(values[0], w);
 if (index >= 0) {
-result[0] = values[1][index];
+return values[0][index];
-return true;
 }
 index = -index - 1; // insert position
-if (index == 0 || index+1 >= values.length) {
+if (index < 1 || index >= values.length) {
 // do not extraploate
-return false;
+return Double.NaN;
 }
-double q1 = values[index  ][0];
+double w1 = values[index-1][0];
-double q2 = values[index+1][0];
+double w2 = values[index  ][0];
-double w1 = values[index  ][1];
+double q1 = values[index-1][1];
-double w2 = values[index+1][1];
+double q2 = values[index  ][1];
-// w1 = m*q1 + b
+// q1 = m*w1 + b
-// w2 = m*q2 + b
+// q2 = m*w2 + b
-// w2 - w1 = m*(q2 - q1)
+// q2 - q1 = m*(w2 - w1)
-// m = (w2 - w1)/(q2 - q1) # q2 != q1
+// m = (q2 - q1)/(w2 - w1) # w2 != w1
-// b = w1 - m*q1
+// b = q1 - m*w1
-if (q1 == q2) {
+if (w1 == w2) {
-result[0] = 0.5*(w1 + w2);
+return 0.5*(q1 + q2);
 }
-else {
-double m = (w2 - w1)/(q2 - q1);
+double m = (q2 - q1)/(w2 - w1);
-double b = w1 - m*q1;
+double b = q1 - m*w1;
-result[0] = q*m + b;
+return w*m + b;
-}
-return true;
 }
 }
 // vim:set ts=4 sw=4 si et sta sts=4 fenc=utf8 :

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