diagonalisation vs diagonalization

diagonalisation and diagonalization both are nouns.

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

As nouns, diagonalisation and diagonalization are synonyms defined as:

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

diagonalisation (noun)	diagonalization (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)