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Effect of multiplying a matrix by a diagonal matrix.



Q. What is the effect of pre-multiplying a matrix



                   ole.gif    



 by a diagonal matrix



                     ole1.gif   




A. The effect is that of multiplying the i-th row of matrix A by the factor ole2.gif i.e. the successive rows of the original matrix are simply multiplied by successive diagonal elements of the diagonal matrix. Explicitly:



    ole3.gif      ole4.gif                                          







Q. What is the effect of post-multiplying a matrix



              ole5.gif    



by a diagonal matrix



                ole6.gif  




A. The effect is that of multiplying the i-th column of matrix A by the factor ole7.gif i.e. the successive columns of the original matrix are simply multiplied by successive diagonal elements of the diagonal matrix. Explicitly:




      ole8.gif      ole9.gif                     


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