S.B. Karavashkin Some peculiarities of derivative of complex function with respect to complex variable (408K, Postscript) ABSTRACT. This paper is the introducing for a monograph devoted to the new branch of theory of complex variable non-conformal mapping. This new original method enables to connect the mathematical models to which the linear modelling is applicable with nonlinear mathematical models, i.e. with the cases when the mapping function is not analytical in a conventional Caushy Riemann meaning but is analytical in general sense and has all the necessary criterions of the analyticity, except of the direct satisfying to the Caushy Riemann equations. As an example, the exact analytical solution of the Bessel-type equation in the continuous range of an independent variable has been obtained