Let M and N be nonzero subspaces of a Hilbert space H,and PM and PN denote the orthogonal projections on M and N,respectively.In this note,an exact representation of the angle and the minimum gap of M and N is obtained.In addition,we study relations between the angle,the minimum gap of two subspaces M and N,and the reduced minimum modulus of(I-PN)PM.
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