In coupled circuit there exists a mutual inductance between the coils. Although mutual inductance M is always a positive quantity, the induced voltage due to mutual inductance may be negative or positive. A dot convention is used to specify the direction of the windings around the core to determine the polarity of the mutual voltage.
Nitin Phadkule (2024). Dot Conventions (https://www.mathworks.com/matlabcentral/fileexchange/100154-dot-conventions), MATLAB Central File Exchange. 取得済み .