Can anyone help me with this StackOverFlow error? Running mergesort

Question

* Write a description of class Sorter here.
* @author (your name)
* @version (a version number or a date)
public class Sorter
     public static long comparisons = 0;
    public static long exchanges   = 0;
    static int M = 10;
    static double aux[];
    static boolean less(double v, double w) {
       comparisons++;
       return (v < w);
    static void exch(double[] a, int i, int j) {
        exchanges++;
        double t=a; a[i]=a[j]; a[j] =t;
private static void compExch(double[] a, int i, int j)
{if (less(a[j], a[i])) exch(a,i,j);}
static int partition(double a[], int l, int r){
int i = l-1, j=r; double v = a[r];
for(;;){
while (less(a[++i],v));
while (less(v,a[--j])) if (j==l) break;
if (i >= j) break;
exch(a,i,j);}
exch(a,i,r);
return i;
static void insertion(double[] a, int l, int r)
{int i;
        for(i=r; i>l; i--) compExch(a, i-1, i);
        {int j = i; double v = a[i];
while(less(v, a[j-1]))
{a[j] = a[j-1]; j--;}
a[j] = v;
static void quicksort(double[] a, int l, int r){
if (r <= l) return;
int i = partition(a,l,r);
quicksort(a,l,i-1);
quicksort(a,i+1,r);
static void Iquicksort(double[]a, int l, int r){
if(r-l <= M) return;
exch(a, (l+r)/2, r-1);
compExch(a,l,r-1);
compExch(a,l,r);
compExch(a,r-1,r);
int i = partition(a,l+1,r-1);
Iquicksort(a,l,i-1);
Iquicksort(a,i+1,r);
static void hybridsort(double a[], int l, int r){
Iquicksort(a,l,r); insertion(a,l,r);}
static void mergeAB(double[] c, int cl, double[] a, int al, int ar, double[] b ,int bl, int br){
int i = al, j=bl;
for (int k = cl; k < cl+ar-al+br-bl+1; k++){
if (i>ar) {c[k] = b[j++]; continue;}
if (j>br) {c[k] = a[i++]; continue;}
c[k] = less(a[i], b[j]) ? a[i++] : b[j++];
static void mergesort(double[] a, int l, int r){
if (r<= 1) return;
int m=(r+1)/2;
mergesort(a,l,m);
mergesort(a,m+1,r);
merge(a,l,m,r);
static int min(int A, int B){return (A<B) ? A : B;}
static void mergesort2(double[] a, int l, int r){
if (r<=1) return;
aux = new double[a.length];
for (int m=1; m <= r-l; m=m+m)
for(int i = l; i <= r-m; i += m+m)
merge(a,i,i+m-1, min(i+m+m-1, r));
static void merge(double[]a, int l, int m, int r){
int i,j;
for (i=m+1; i>l; i--) aux[i-1] = a[i-1];
for (j=m; j<r; j++) aux[r+m-j] = a[j+1];
for (int k = 1; k <= r; k++)
if (less(aux[j], aux[i]))
a[k]=aux[j--]; else a[k]=aux[i++];
* Write a description of class SortClient here.
* 10-15-06
public class SorterClient
     public static void main(String[] args) {
int N = 1000;
int times = 1;
System.out.println("ALGORITHM comp=COMPARISONS exch=EXCHANGES");
System.out.println("---------------------------------------------------------------------------------------------");
System.out.println();
System.out.println("Selection: ");
while(times<4){
if(times==2){N=3000;}
if(times==3){N=10000;}
// generate N random real numbers between 0 and 1
long start = System.currentTimeMillis();
double[] a = new double[N];
for (int i = 0; i < N; i++)
{a[i] = Math.random();}
long stop = System.currentTimeMillis();
double elapsed = (stop - start) / 1000.0;
// sort them
Sorter test = new Sorter();
start = System.currentTimeMillis();
test.mergesort(a, 0, a.length - 1);
stop = System.currentTimeMillis();
elapsed = (stop - start) / 1000.0;
System.out.print(elapsed + "secs ");
System.out.print("N=" + N + "= ");
System.out.print(" " + Sorter.comparisons + "comp");
System.out.println(" " + Sorter.exchanges + "exch");
times++;

Answer 1

I get it in the mergesort method while program is running line,
mergesort(a,l,m);
quicksort runs fine.