A problem of economical discretization of equations, arising at the finite-section approximation of Fredholm integral equations of the first kind on the half-line, are investigated. The piecewise-constant discretization schemes providing given accuracy are developed for finite-section equations. The order estimates for the volume of used discrete information are calculated. The comparative analysis of the information expenses for proposed schemes and known earlier is given.Consider the Fredholm integral equation of the first kind on the half-lineunder the assumption thatis given and for any s > 0 the following relation holdsSubstituting this equality into (1), we obtain the equationWe assume that in (3)and for some reals α, ω > 1/2 the kernel a(t, τ ) satisfies the relationExample. The equation2 dτ = y(t) describes the distribution of the size of spherical particles by the scattering method [2]. Here, J 1 is the Bessel function of order 1 and x is the unknown distribution of the particle size. As is known [3], conditions (2) hold for κ = 3 and β = 4. The kernel a(t, τ ) = [
which arises after the change of variables x(t) = (1 + t)−s/2 z(t), satisfies condition (5) with α = 2 and ω = s 2 − 2, where s > 5.is the characteristic function of the interval [0, M). Following the finite-section method, we pass from (3) to the equationTo construct finite-dimensional approximations to the exact solution of equation (3), we must discretize the kernel and righthand side of equation (6). Following [3], [4], we set M = 2 m , N = 2 n , where m, n are some integers, and consider the system of nodesHere 0 < θ ≤ 1 and q ∈ N are fixed numbers and [u] denotes the integer part of u.