The calculation of the spatial changes of the amplitude and phase of the order parameter was performed in the Python environment with the use of the Skipy and JiTCODE libraries.

In [N(CH_{3})_{4}]_{2}CuCl_{4} crystals, there is an incommensurate phase *I*_{1} at the small values of the magnitude of long-range interaction (*T*<0.6) and an incommensurate phase *I*_{2} at *T*≥1.0. This is the same incommensurate phase, although the behavior of the amplitude and phase functions in it is different under the different conditions mentioned above. At *T* = 0.6 ÷ 1.0, the coexistence of these two phases is observed which is manifested in the absence of anomalous changes of q during the transition from the sinusoidal mode of IC modulation to the soliton regime

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