identity operator
Mathematical term for an operator that maps each element to itself. Used in functional analysis and linear algebra.
The identity operator maps any vector to itself.
恒等写像 is the identity mapping (often used in set theory and general mathematics), while 恒等作用素 specifically refers to the identity operator in the context of vector spaces and functional analysis.
Compound of 恒等 (identity, equality) and 作用素 (operator). The term is a direct calque from English 'identity operator'.