TheAlgorithms/JavaScript · error · Error

Square matrix is required.

Error message

Square matrix is required.

What it means

Thrown by determinant(matrix) (Determinant.js:62) as a plain Error when the matrix passes the structural check but is not square. The helper isMatrixSquare (Determinant.js:43) verifies that every row has length equal to the number of rows. The Laplace expansion algorithm requires a square matrix, so a non-square input is rejected. A 1x1 matrix returns its single element without throwing.

Source

Thrown at Maths/Determinant.js:62

  let numRows = matrix.length
  for (let i = 0; i < numRows; i++) {
    if (numRows !== matrix[i].length) {
      return false
    }
  }
  return true
}

const determinant = (matrix) => {
  if (
    !Array.isArray(matrix) ||
    matrix.length === 0 ||
    !Array.isArray(matrix[0])
  ) {
    throw new Error('Input is not a valid 2D matrix.')
  }
  if (!isMatrixSquare(matrix)) {
    throw new Error('Square matrix is required.')
  }
  let numCols = matrix[0].length
  if (numCols === 1) {
    return matrix[0][0]
  }
  let result = 0
  let setIndex = 0
  for (let i = 0; i < numCols; i++) {
    result +=
      Math.pow(-1, i) *
      matrix[setIndex][i] *
      determinant(subMatrix(matrix, setIndex, i))
  }
  return result
}
export { determinant }

View on GitHub (pinned to 5c39e87a9a)

Solutions

1. Verify squareness before calling: m.every(row => row.length === m.length).
2. If you need the determinant of a non-square matrix, reconsider — it is undefined; you may want SVD or a different decomposition.
3. Validate row lengths during data loading and reject ragged input early.
4. Log matrix dimensions at the call site to catch dimension mismatches during debugging.

Example fix

// before
const d = determinant(m) // throws if m is not square

// after
const isSquare = Array.isArray(m) && m.length > 0 &&
  m.every(row => Array.isArray(row) && row.length === m.length)
if (!isSquare) throw new Error('expected a square matrix')
const d = determinant(m)

const isSquare = Array.isArray(matrix) && matrix.length > 0 &&
  matrix.every(row => Array.isArray(row) && row.length === matrix.length)
if (!isSquare) throw new Error('expected a square matrix')
const d = determinant(matrix)

const isSquareMatrix = (v) => Array.isArray(v) && v.length > 0 &&
  v.every(row => Array.isArray(row) && row.length === v.length)

try {
  d = determinant(matrix)
} catch (e) {
  if (e instanceof Error && /Square matrix/.test(e.message)) {
    // non-square — reconsider whether determinant is the right operation
  } else throw e
}

When it happens

Trigger: Call determinant([[1,2,3],[4,5,6]]) — a 2x3 matrix; determinant([[1,2],[3,4],[5,6]]) — a 3x2 matrix; a matrix with a ragged row like [[1,2],[3]] returns false from isMatrixSquare and throws here.

Common situations: Loading data with inconsistent row lengths from CSV; transposing or slicing that changed dimensions; passing a data table with a header row of different length; construction loop with an off-by-one column count.

Related errors

• Input is not a valid 2D matrix.
• Input is not a valid 2D matrix.
• Duplicate characters in character set are not allowed
• Not a valid character: ${digit}
• Argument is not a valid HEX code!

AI-assisted analysis of TheAlgorithms/JavaScript@5c39e87a9a (2026-08-13). Data as JSON: /api/errors/ffd62672ae3228a9. Report an issue: GitHub.