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During the given work several gradient procedures of search of local extremums have been tested. Their

**Such specificity
of variables has allowed to use effectively at the second stage of experiments
the gradient procedure in which moving on all variables of eight-parametrical
conformity measure is carried out simultaneously and basically is independent.
During searching delays are possible (misses of steps on some variables)
if parameters with higher priority were not arranged yet. In final variant
the following system of priorities was used: (+, A), (P1, P2), (D), (B1,
B2, =) where - "+" and "=" designate moving in cross and longitudinal
directions accordingly. The step on any variable increases half (with
the count of restriction on maximum value - see further) if the it is
executed in the same direction, as previous, and decreases otherwise. Thus
it is considered, that those variables were arranged, the step on which
became less, than 1/4 from the maximum admissible value on the given variable.**

**The last values
were chosen from the most common reasons so that as a result of each
step the new approximating segment not too overstepped the bounds of
old onethe. Steps in a longitudinal direction (and on length of the branches)
were limited to value B/2, and in cross - D/2. Steps on the angle and
curvature should not oscillate ends of the segment on value bigger than
D/2, i.e.
A*MAX(B1, B2)/0.7 and
P * (B/0.7)/2 should not exceed D/2. In order to prevent discretization
disclosures of analysed contours, the value of parameter D was limited
from below to the value ranging 0.5 - 2.5 distances between adjacent points
of the raster. From above parameter D was limited by value B/2.**

**Particularly
such restrictions are organized so, that at the approach to one of them
it is authorized to make the following step only on half of the distance
before this restriction. It simply enough ensures a possibility of increase
of a step if a necessity of movement in the opposite direction exists.
Initial steps on separate components were chosen equal to the half of
their greatest possible values. Thus initial values of parameters B and
D were accepted equal 10 and 4 accordingly, and as much as the possible
admissible step value on D equal 0.5. Search procedure of the next conformity
measure maximum stopped when steps on all variables became smaller, than
0.2 of their maximum possible admissible values.**

**As a rule, search
of the maximums corresponding to contour segments required on the average
60-80 steps on theof declination angle and position in the cross direction
at 8-12 steps in the longitudinal direction. **