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new algorithm for matrix determinant #161

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24 changes: 12 additions & 12 deletions lib/numbers/matrix.js
Original file line number Diff line number Diff line change
Expand Up @@ -274,20 +274,20 @@ matrix.determinant = function (m) {
} else if (numRow === 2) {
return m[0][0] * m[1][1] - m[0][1] * m[1][0];
}

for (col = 0; col < numCol; col++) {
diagLeft = m[0][col];
diagRight = m[0][col];

for (row = 1; row < numRow; row++) {
diagRight *= m[row][(((col + row) % numCol) + numCol) % numCol];
diagLeft *= m[row][(((col - row) % numCol) + numCol) % numCol];
var indexColumn = 0;
var result = 0;
var numberOfAddedRows = 0;
while(indexColumn < numCol){
numberOfAddedRows = 0;
var newArray = new Array();
while(numberOfAddedRows < numRow - 1){
newArray.push(m[numberOfAddedRows + 1].slice(0, indexColumn).concat(m[numberOfAddedRows + 1].slice(indexColumn + 1)))
numberOfAddedRows++;
}

det += diagRight - diagLeft;
result += Math.pow(-1, indexColumn) * m[0][indexColumn] * matrix.determinant(newArray);
indexColumn++;
}

return det;
return result;
};

/**
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