Through the first part of the paper, primitive network matrices, incidence matrices, and the method of their formation are theoretically defined. In the second part of the paper, the procedures for forming the impedance and admittance matrix of the node are listed and processed. In the last part of the work, expressions for the calculation of currents through the branches and node voltages in the event of a three-pole short circuit were derived. Finally, on the example of the electrical network, a comparison was made of the results obtained for currents through the branches and voltages on the busbars, obtained with the help of a program developed in the MATLAB environment, with the results obtained with the help of the TOKSwin program package.