diff flys-artifacts/src/main/java/de/intevation/flys/utils/DoubleUtil.java @ 3806:881fcd01e056

merged flys-artifacts/pre2.6-2011-11-04
author Thomas Arendsen Hein <thomas@intevation.de>
date Fri, 28 Sep 2012 12:14:50 +0200
parents 0b6dac664bbb
children 0dd58ab7e118
line wrap: on
line diff
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/flys-artifacts/src/main/java/de/intevation/flys/utils/DoubleUtil.java	Fri Sep 28 12:14:50 2012 +0200
@@ -0,0 +1,136 @@
+package de.intevation.flys.utils;
+
+import java.util.Arrays;
+
+import de.intevation.flys.artifacts.math.Linear;
+
+
+public class DoubleUtil
+{
+    public static final double DEFAULT_STEP_PRECISION = 1e6;
+
+    private DoubleUtil() {
+    }
+
+    public static final double [] explode(double from, double to, double step) {
+        return explode(from, to, step, DEFAULT_STEP_PRECISION);
+    }
+
+    public static final double round(double x, double precision) {
+        return Math.round(x * precision)/precision;
+    }
+
+    public static final double round(double x) {
+        return Math.round(x * DEFAULT_STEP_PRECISION)/DEFAULT_STEP_PRECISION;
+    }
+
+    public static final double [] explode(
+        double from,
+        double to,
+        double step,
+        double precision
+    ) {
+        double lower = from;
+
+        double diff = to - from;
+        double tmp  = diff / step;
+        int    num = (int)Math.abs(Math.ceil(tmp)) + 1;
+
+        double [] values = new double[num];
+
+        if (from > to) {
+            step = -step;
+        }
+
+        double max = Math.max(from, to);
+
+        for (int idx = 0; idx < num; idx++) {
+            if (lower > max) {
+                return Arrays.copyOfRange(values, 0, idx);
+            }
+
+            values[idx] = round(lower, precision);
+            lower      += step;
+        }
+
+        return values;
+    }
+
+    public static final double interpolateSorted(
+        double [] xs,
+        double [] ys,
+        double x
+    ) {
+        int lo = 0, hi = xs.length-1;
+
+        int mid = -1;
+
+        while (lo <= hi) {
+            mid = (lo + hi) >> 1;
+            double mx = xs[mid];
+                 if (x < mx) hi = mid - 1;
+            else if (x > mx) lo = mid + 1;
+            else return ys[mid];
+        }
+        if (mid < lo) {
+            return lo >= xs.length
+                ? Double.NaN
+                : Linear.linear(x, xs[mid], xs[mid+1], ys[mid], ys[mid+1]);
+        }
+        return hi < 0
+            ? Double.NaN
+            : Linear.linear(x, xs[mid-1], xs[mid], ys[mid-1], ys[mid]);
+    }
+
+    public static final boolean isIncreasing(double [] array) {
+        int inc = 0;
+        int dec = 0;
+        int sweet = (array.length-1)/2;
+        for (int i = 1; i < array.length; ++i) {
+            if (array[i] > array[i-1]) {
+                if (++inc > sweet) {
+                    return true;
+                }
+            }
+            else if (++dec > sweet) {
+                return false;
+            }
+        }
+        return inc > sweet;
+    }
+
+    public static final double [] swap(double [] array) {
+        int lo = 0;
+        int hi = array.length-1;
+        while (hi > lo) {
+            double t  = array[lo];
+            array[lo] = array[hi];
+            array[hi] = t;
+            ++lo;
+            --hi;
+        }
+
+        return array;
+    }
+
+    public static final double [] swapClone(double [] in) {
+        double [] out = new double[in.length];
+
+        for (int j = out.length-1, i = 0; j >= 0;) {
+            out[j--] = in[i++];
+        }
+
+        return out;
+    }
+
+    public static final double [] sumDiffs(double [] in) {
+        double [] out = new double[in.length];
+
+        for (int i = 1; i < out.length; ++i) {
+            out[i] = out[i-1] + Math.abs(in[i-1] - in[i]);
+        }
+
+        return out;
+    }
+}
+// vim:set ts=4 sw=4 si et sta sts=4 fenc=utf8 :

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