  The work presents an integral solution of the time-fractional subdiffusion
through a preliminary defined profile with unknown coefficients and the concept
of penetration layer well known from the heat diffusion The profile satisfies
the boundary conditions imposed at the boundary of the boundary layer in a weak
form that allows its coefficients to be expressed through the boundary layer
depth as unique parameter describing the profile. The technique is demonstrated
by a solution of a time fractional subdiffusion equation in rectilinear 1-D
conditions
