MathDB
Performing operations on a matrix by keeping invariance

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October 13, 2010
linear algebramatrixfloor functionceiling functionlinear algebra unsolved

Problem Statement

For a matrix (pij)(p_{ij}) of the format m×nm\times n with real entries, set ai=j=1npij for i=1,,m and bj=i=1mpij for j=1,...,n(1)a_i =\displaystyle\sum_{j=1}^n p_{ij}\text{ for }i = 1,\cdots,m\text{ and }b_j =\displaystyle\sum_{i=1}^m p_{ij}\text{ for }j = 1, . . . , n\longrightarrow(1) By integering a real number, we mean replacing the number with the integer closest to it. Prove that integering the numbers ai,bj,pija_i, b_j, p_{ij} can be done in such a way that (1)(1) still holds.