Let \(L\) be the Leontief inverse. Then the multiplier product matrix \(M\) is calculated as follows:
$$M = 1/v L_c L_r$$
where \(v = t(1) L 1\) such that \(1\) is a column matrix of ones, \(L_c = L 1\) is a column matrix of row sums, and \(L_r = t(1) L\) is a row matrix of column sums.
References
Nazara, Suahasil & Guo, Dong & Hewings, Geoffrey J.D., & Dridi, Chokri, 2003. "PyIO. Input-Output Analysis with Python". REAL Discussion Paper 03-t-23. University of Illinois at Urbana-Champaign. (http://www.real.illinois.edu/d-paper/03/03-t-23.pdf)