三さん角かく行ぎょう列れつ

noun

triangular matrix

A square matrix where all entries above or below the main diagonal are zero. Used in linear algebra.

• 三さん角かく行ぎょう列れつの行ぎょう列れつ式しきは対たい角かく成せい分ぶんの積せきに等ひとしい。

  The determinant of a triangular matrix equals the product of its diagonal entries.