noun
submatrix
Technical term in linear algebra; refers to a matrix formed by selecting a subset of rows and columns from a larger matrix.
この部分行列の行列式を計算してください。
Please calculate the determinant of this submatrix.
行列 means 'matrix' in mathematics; 部分行列 is a submatrix, a part of a matrix.
Compound of 部分 (part) and 行列 (matrix).