matrix - Strassen Multiplication Algorithm StackOverFlow Error -


i working on implementing straussen's multiplication. below method multiplying them in divide , conquer approach.

public static double[][] multiply(double[][] a, double[][] b)      {                  int n = a.length;          double[][] r = new double[n][n];          /** base case **/          //if (n == 1){            //  r[0][0] = a[0][0] * b[0][0];        // }          //else{              double[][] a11 = new double [n/2][n/2];              double[][] a12 = new double [n/2][n/2];              double[][] a21 = new double [n/2][n/2];              double[][] a22 = new double [n/2][n/2];              double[][] b11 = new double [n/2][n/2];              double[][] b12 = new double [n/2][n/2];              double[][] b21 = new double [n/2][n/2];              double[][] b22 = new double [n/2][n/2];                /** dividing matrix 4 halves **/              split(a, a11, 0 , 0);              split(a, a12, 0 , n/2);              split(a, a21, n/2, 0);              split(a, a22, n/2, n/2);              /** dividing matrix b 4 halves **/              split(b, b11, 0 , 0);              split(b, b12, 0 , n/2);              split(b, b21, n/2, 0);              split(b, b22, n/2, n/2);                /**                 m1 = (a11 + a22)(b11 + b22)                m2 = (a21 + a22) b11                m3 = a11 (b12 - b22)                m4 = a22 (b21 - b11)                m5 = (a11 + a12) b22                m6 = (a21 - a11) (b11 + b12)                m7 = (a12 - a22) (b21 + b22)              **/                double [][] m1 = multiply(add(a11, a22), add(b11, b22));              double [][] m2 = multiply(add(a21, a22), b11);              double [][] m3 = multiply(a11, sub(b12, b22));              double [][] m4 = multiply(a22, sub(b21, b11));              double [][] m5 = multiply(add(a11, a12), b22);              double [][] m6 = multiply(sub(a21, a11), add(b11, b12));              double [][] m7 = multiply(sub(a12, a22), add(b21, b22));                /**                c11 = m1 + m4 - m5 + m7                c12 = m3 + m5                c21 = m2 + m4                c22 = m1 - m2 + m3 + m6              **/              double [][] c11 = add(sub(add(m1, m4), m5), m7);              double [][] c12 = add(m3, m5);              double [][] c21 = add(m2, m4);              double [][] c22 = add(sub(add(m1, m3), m2), m6);                /** join 4 halves 1 result matrix **/              join(c11, r, 0 , 0);              join(c12, r, 0 , n/2);              join(c21, r, n/2, 0);              join(c22, r, n/2, n/2);            /** return result **/              return r;      }

in order implement code, reading in 2 txt files, 1 matrix , 1 matrix b. terms of testing have 2 matrices being exact same:

5

3.250 6.130 3.180 7.680 9.060

5.450 1.660 6.790 6.650 4.250

4.460 8.260 7.870 7.880 1.890

1.460 8.510 8.510 3.510 1.440

1.590 7.160 4.400 3.310 1.970

where first line n, , following lines matrix.

my problem getting stack overflow error on line

int n = a.length;

which can't seem figure out why or look. question is, problem lie in algorithm? or problem in main method?


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