The orthogonal algorithms possessing big speed, than algorithms of the first group. Realization on the COMPUTER demands them 75-100 times less calculations in comparison with wave algorithms. Such algorithms apply at design of printed-circuit boards with the through metallized openings. Shortcomings of this group of algorithms are connected with receiving a large number of transitions from a layer to a layer, lack of a 100% guarantee of carrying out routes, a large number in parallel of the going conductors;
The algorithms using consecutive process of fixing of elements in positions are the most high-speed now. However on quality of the received decision consecutive algorithms concede to the iterative. Therefore they are used usually for receiving initial placement of elements on a payment.
The main lack of consecutive algorithm is inability to find a global minimum of quantity of external relations (possible situations are not analyzed). The greatest efficiency of a method of consecutive splitting the count takes place, when number of tops column G much more tops in any part of splitting.
All cells of an assembly field subdivide on busy and free. Cells in which the conductors constructed on the previous steps are already located are considered busy or there are assembly conclusions of elements, and also the cells corresponding to border of a payment and sites forbidden for making of conductors. Every time when carrying out the new route it is possible to use only free cells which number in process of carrying out routes is reduced.
If it is some such tops, the preference is given to top with the maximum number of multiple edges. From a set of the tops adjacent to tops of the formed piece the column G1(X1,U, choose that which provides the minimum increment of communications of a piece with even unallotted tops. This top of xi X \X1 is included in G1(X1,U if there is no violation of restriction on number of external relations of a piece, i.e.
Shortcomings are labor input of a method and complexity of its realization (selection of coefficients for power communications); need of fixation of location of some number of constructive elements on a payment for prevention of big unevenness of their placement on separate sites of a payment.
where I and J – sets of indexes of the tops belonging to XB and XA. In this expression the first two composed define number of the edges connecting xg tops to GB(XB,UB) and xh with GA(XA,UA), and presence of the third member is caused by that communication of two composed was considered twice.
On a matrix of contiguity of the initial count | αhp|NxN where by N – number of tops of the initial count (at great value of N for reduction of volume of random access memory of the COMPUTER it is used not a matrix of contiguity, but its code realization), we determine local degrees of tops.
Simultaneous optimization of all connections at trace due to search of all options it is impossible now. Therefore generally locally optimum methods of trace when the route is optimum only on this step in the presence of earlier carried out connections are developed.
Iterative algorithms have the structure similar to the iterative algorithms of configuration considered earlier. For improvement of initial placement of elements on a payment enter iterative process of shift into them places of couples of elements.
Algorithms of heuristic type. These algorithms are partially based on heuristic reception of search of a way in a labyrinth. Thus each connection is carried out on the shortest way, bypassing the obstacles which are found on the way.
If the adjusting sizes of all elements placed on a payment are identical, the element chosen on the next step fix in that position from among unoccupied, for which value of criterion function taking into account earlier placed Rl-1 elements minimum. In particular, if criterion of an optimality is the minimum of the total weighed length of connections,
where αjε – a contiguity matrix element initially column G (X, U); δ (xg) – the relative weight of top of xg, G1(X1,U equal to an increment of number of external edges of a piece at inclusion of top of xg in a set of X1; E – a set of indexes of the tops included in the formed piece of the count on the previous steps of algorithm; m – the most admissible number of external relations of separately taken piece with all remained.