X-Git-Url: https://git.gag.com/?a=blobdiff_plain;ds=sidebyside;f=core%2Fsrc%2Fnet%2Fsf%2Fopenrocket%2Futil%2FArrayUtils.java;h=59290b12d9c8fd48401436ad62bf93dffc2330f4;hb=cb6cee5e14451dd9b852723a30a5fbdee404d959;hp=67209f323ea4a0db5b5fa014cfdfab96c15744c4;hpb=0be17fea9df8667c018922d9eca1166254dce470;p=debian%2Fopenrocket

diff --git a/core/src/net/sf/openrocket/util/ArrayUtils.java b/core/src/net/sf/openrocket/util/ArrayUtils.java
index 67209f32..59290b12 100644
--- a/core/src/net/sf/openrocket/util/ArrayUtils.java
+++ b/core/src/net/sf/openrocket/util/ArrayUtils.java
@@ -4,6 +4,132 @@ import java.lang.reflect.Array;
 
 public class ArrayUtils {
 
+	/**
+	 * Returns a double array with values from start to end with given step.
+	 * Starts exactly at start and stops at the step before stop is reached. 
+	 */
+	public static double[] range(double start, double stop, double step){
+		
+		int size = (int) Math.floor(((stop - start) / step));
+		
+		//System.out.println("Range from "+start+" to "+stop+" step "+step+" has length "+size);
+		
+		double[] output = new double[size];
+		int i = 0;
+		double x = start;
+		while (i<size){
+			output[i] = x;
+			x = x+step;
+			i++;
+		}
+		
+		return output;
+	}
+
+	/**
+	 * Return the mean of an array
+	 */
+	public static double mean(double[] vals){
+		double subtotal = 0;
+		for (int i = 0; i < vals.length; i++ ){
+			subtotal += vals[i];
+		}
+		subtotal = subtotal / vals.length;
+		return subtotal;
+	}
+
+	/**
+	 * Returns the maximum value in the array.
+	 */
+
+	public static double max(double[] vals) {
+		double m = vals[0];
+		for (int i = 1; i < vals.length; i++)
+			m = Math.max(m, vals[i]);
+		return m;
+	}
+
+	/**
+	 * Returns the minimum value in the array.
+	 */
+
+	public static double min(double[] vals) {
+		double m = vals[0];
+		for (int i = 1; i < vals.length; i++)
+			m = Math.min(m, vals[i]);
+		return m;
+	}
+
+	/**
+	 * Returns the variance of the array of doubles
+	 */
+	public static double variance(double[] vals) {
+		double mu = mean(vals);
+		double sumsq = 0.0;
+		double temp = 0;
+		for (int i = 0; i < vals.length; i++){
+			temp = (mu - vals[i]);
+			sumsq += temp*temp;
+		}
+		return sumsq / (vals.length);
+	}
+
+	/**
+	 * Returns the standard deviation of an array of doubles
+	 */
+	public static double stdev(double[] vals) {
+		return Math.sqrt(variance(vals));
+	}
+	
+	/**
+	 * Returns the RMS value of an array of doubles 
+	 */
+	public static double rms(double[] vals) {
+		double m = mean(vals);
+		double s = stdev(vals);
+		return Math.sqrt( m*m + s*s );
+	}
+	
+	/**
+	 * Returns the integral of a given array calculated by the trapezoidal rule
+	 * dt is the time step between each array value
+	 */
+	public static double trapz(double[] y, double dt){
+		double stop = y.length * dt;
+		
+		if (y.length <= 1 || dt <= 0) return 0;
+		
+		double[] x = range(0, stop, dt);
+	    
+	    double sum = 0.0;
+	    for (int i = 1; i < x.length; i++) {
+	        sum += (x[i] - x[i-1]) * (y[i] + y[i-1]);
+	    }
+	    return sum * 0.5;
+	}
+	
+	/**
+	 * Returns the nearest value in an array to a given value
+	 * Search starts from the lowest array index
+	 */
+	public static double tnear(double[] range, double near, double start, double step){
+		double min = Double.POSITIVE_INFINITY;
+		int mini = 0;
+		
+		//System.out.println("Nearest to "+near+" in range length "+range.length);
+		for (int i=0; i < range.length; i++){
+			double x = Math.abs(range[i] - near);
+			if (x < min){
+				min = x;
+				mini = i;
+			}
+		}
+		
+		//System.out.println("Found nearest at i="+mini);		
+		return start + (mini*step);
+	}
+	
+	
 	public static <T> T[] copyOf( T[] original, int length ) {
 		return copyOfRange(original,0,length);
 	}
@@ -114,3 +240,4 @@ public class ArrayUtils {
 	}
 
 }
+