diagonalization vs diagonalisation

diagonalization and diagonalisation both are nouns.

Word	Noun	Adjective	Verb	Adverb
diagonalization	Yes	No	No	No
diagonalisation	Yes	No	No	No

As nouns, diagonalization and diagonalisation are synonyms defined as:

diagonalization and diagonalisation: changing a square matrix to diagonal form (with all non-zero elements on the principal diagonal)

diagonalization (noun)	diagonalisation (noun)
changing a square matrix to diagonal form (with all non-zero elements on the principal diagonal)	changing a square matrix to diagonal form (with all non-zero elements on the principal diagonal)