[SOLVED] Calculating Std. Deviation using Java

• 12-12-2008, 07:23 AM
random0munky
[SOLVED] Calculating Std. Deviation using Java
I'm sure this has been posted before, but I'm just having a little tough time with it. The sum and mean calculates correctly but for some reason the standard deviation doesn't calculate correctly, here's my code. Any help is great appreciated =D

Code:

```        private static double stddev(double[] doubleArray) {                 int i ;                 double avg = 0 ;                 double sum = 0 ;                 double tempSum = 0 ;                                 // sum of the array             for(i = 0; i < doubleArray.length; i++) {                 sum = sum + doubleArray[i] ;                 System.out.println(sum) ;             }                         // average of the array             avg = sum / (doubleArray.length) ;             System.out.println("Mean = " + avg) ;                         // the length of the array minus 1             tempSum = (doubleArray.length) - 1 ;             // (x - average of x's)^2             for(i = 0; i < doubleArray.length; i++) {             sum = sum + (Math.abs(doubleArray[i] - avg) * Math.abs(doubleArray[i] - avg)) ;             }                         // (x - average of x's)^2 divided by length of the array minus 1             sum = sum / tempSum ;         if (i == 0) {                 return 0.0 ;                                        }                 // sqrt of the above     return Math.sqrt(sum) ; } public static void main(String[] args) {         //***********************************************************         // Testing standard deviation         System.out.println("Testing variance\n");         double[] testDoubleArray = { 2.0, -3, 5, 6.0, 0.0 };         // You should try these test cases too         //double[] testDoubleArray = { 2.0, 2.0 };         //double[] testDoubleArray = {}         System.out.println("Test array for standard deviation is: ");         for (i=0; i < testDoubleArray.length; i++) {                 System.out.print(testDoubleArray[i] + " ");         }         System.out.println("\nStandard deviation is: " + stddev(testDoubleArray));         System.out.println("\n***************************");```
Just to let you know but I need to have it in this format, but what I'm stuck on is the calculations part. Thank you =D
• 12-12-2008, 10:24 AM
random0munky
Never mind I solved it