  The magnetic field integrals connected with the momentum resolution are
calculated for the ATLAS inner tracking volume in a range of pseudorapidity
$|\eta| < 3$ for the cases of `ideal' and inhomogeneous solenoid fields. In the
latest case, the magnetic field map is extracted from POISSON calculations with
help of an interface program POISGT. The tracking volume is restricted by a
length of 6.8 m and by a radius of 1.06 m. The solenoid coil with an active
length of 6.3 m and with an inner radius of 1.23 m produces the magnetic flux
density of 2 T in the center of the coil.
