Mathematical term for the change in a function or functional, often used in calculus of variations.
The calculus of variations is a method for finding extrema of functionals.
この方程式の変分を計算してください。
Please calculate the variation of this equation.
Compound of 変 (change) and 分 (part, segment), likely a calque from English 'variation' or German 'Variation' in mathematical contexts.