Peculiarity of some nonperiodical signals Fourier transform definition

The special features of Fourier transform practical definition of nonperiodical signals independent of frequency band are considered. For Fourier transform definition of such signals represented by discrete samples, preliminary restoration of continuous signals by interpolation of the third or higher degrees Lagrange interpolational splines is described. With an example of interpolation polynomial Lagrange of the third degree, formulas for Fourier transform definition of a signal on a discrete grid of frequencies are shown. The errors of Fourier transform definition of an exponential signal represented by Lagrange interpolational splines of the second and higher degree are analyzed.