let n be Nat; :: thesis: for M2, M1 being Matrix of n, REAL st M2 is_less_or_equal_with M1 holds
M1 - M2 is Nonnegative
let M2, M1 be Matrix of n, REAL ; :: thesis: ( M2 is_less_or_equal_with M1 implies M1 - M2 is Nonnegative )
assume A1: M2 is_less_or_equal_with M1 ; :: thesis: M1 - M2 is Nonnegative
A2: ( Indices M1 = [:(Seg n),(Seg n):] & Indices M2 = [:(Seg n),(Seg n):] & Indices (M1 - M2) = [:(Seg n),(Seg n):] ) by MATRIX_1:25;
A3: ( len M1 = len M2 & width M1 = width M2 ) by Lm1;
for i, j being Nat st [i,j] in Indices (M1 - M2) holds
(M1 - M2) * i,j >= 0

proof

let i, j be Nat; :: thesis: ( [i,j] in Indices (M1 - M2) implies (M1 - M2) * i,j >= 0 )
assume A4: [i,j] in Indices (M1 - M2) ; :: thesis: (M1 - M2) * i,j >= 0
then M1 * i,j >= M2 * i,j by A1, A2, Def6;
then (M1 * i,j) - (M2 * i,j) >= 0 by XREAL_1:50;
hence (M1 - M2) * i,j >= 0 by A2, A3, A4, Th3; :: thesis: verum

end;

hence M1 - M2 is Nonnegative by Def4; :: thesis: verum