i write code contain vector of legth 1000 that vector split into two vectors of same length follow specific algorithm , this two vectors multiply into inverse of two matrices that should be the same length of vectors 1000. but i face problem when compute inverse matrix cause the big length ArrayIndexOutOfBoundsException appear : here is part of the code which the problem appear:
public static double determinant(Matrix M) {
if(M.size()==1){
return M.getValueAt(0, 0); }
if(M.size()==2){
return(M.getValueAt(0, 0)*(M.getValueAt(1, 1)))-((M.getValueAt(0, 1)*(M.getValueAt(1, 0)))); }
double sum = 0.0;
for (int i = 0; i < 1000; i++) {
sum += changeSign(i) * M.getValueAt(0, i) * determinant(createSubMatrix(M, 0, i)); }
return sum; }
public static Matrix createSubMatrix(Matrix M, int excluding_row, int excluding_col) {
Matrix mat = new Matrix(999,999); int r = -1;
for (int i = 0; i < 1000; i++) {
if (i == excluding_row) {
continue; } r++;
int c = -1;
for (int j = 0; j < 1000; j++) {
if (j == excluding_col) {
continue; }
mat.setValueAt(r, ++c, M.getValueAt(i, j)); } } return mat; }
the Exception is :
Exception in thread "AWT-EventQueue-0" java.lang.ArrayIndexOutOfBoundsException: 999 at searchencrypted.Matrix.getValueAt(Matrix.java:102) at searchencrypted.Matrix.createSubMatrix(Matrix.java:84) at searchencrypted.Matrix.determinant(Matrix.java:64)
All for loops are indexed in the range 0-999, that's 1000 iterations.
But the matrix is initialized with 999 elements.
1000th iteration throws that error. [Second line of exception message]
@ Umesh Worlikar , how solve this problem, if i make length of submatrix the same of iterations it output stackoverflow error , and if i make the iterationa same of submatrix length it output outofmemory error java heap space.
Both stackoverflow and outofmemory errors indicate that memory resources are not carefully conserved. I would suggest referring learning resources on differences between stack and heap. This is language independent, but there may be plenty of training material available with Java examples. For example this one: [https://www.journaldev.com/4098/java-heap-space-vs-stack-memory]
As a general guideline:
One should avoid passing large data structures to functions by values. This over-kills the stack space. This is especially true for Matrices which are almost always passed by reference.
One the other hand, outOfMemory indicates that program is allocating large data structures on heap, which are probably not cleaned up quickly after their usage. Smaller objects with shorter life-spans are always preferable, but again it's a matter of solution choice.
For a Java code, it would be also useful to understand Garbage Collection Mechanism to get the best out of available heap memory.
Only the first answer is relevant for this case, as a java.lang.ArrayIndexOutOfBoundsException is thrown. Indeed, the matrix needs to be initialized with 1000 elements instead of 999.
Dear Amal,
use big integer package , and algorithms for addition, and multiplication.
thanks
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