Hello Dima, the red area exist for:
xamin < xbmin or xamax > xbmax or yamin < ybmin or yamax < ybmax This cannot be described in an LP, but in a MILP: binaries xb1, xb2, yb1, yb2; constant M sufficiently high; (xbmin - xamin) - M * xa1 <= 0; (xamax - xbmax) - M * xb1 <= 0; (ybmin - yamin) - M * ya1 <= 0; (yamax - ybmax) - M * yb1 <= 0; (xbmin - xamin) + M * (1-xa1) >= 0; (xamax - xbmax) + M * (1-xb1) >= 0; (ybmin - yamin) + M * (1-ya1) >= 0; (yamax - ybmax) + M * (1-yb1) >= 0; An area of a outside of b exist if sum(xb1, xb2, yb1, yb2) > 0 Best regards Xypron -------- Original-Nachricht -------- > Datum: Sat, 19 Apr 2008 17:30:05 +0400 > Von: Dima Ry <[EMAIL PROTECTED]> > An: [email protected] > Betreff: [Help-glpk] help to formulate problem in terms of LP > > I currently deal with parallelepipeds. The task is to know is one > parallelepiped itersects other one. The geometry shown at picture : > http://www.nabble.com/file/p16782979/lp_question.gif > > I need to know is the red area of parallelepiped "a" exists or not. The > red > area can be found as intersection of "a" internal area and "b" external > area. If intersection exists then "a" intersects "b" > > If where a way to solve this task using LP? > > > There is no problem to express internal area in terms of LP. But i wonder > if external area of "b" can be expressed? > > I tried following : > for "a" following constraints : > x >= 1 > x <= 3 > y >= 2 > y <= 3 > > for "b" > x <= 2 > x >= 4 > y <= 1 > y >= 4 > > Since all equation are connected with "and" operator thus "x <= 2 and x >= > 4" will issue "no solution" > > Thanks in advance for any ideas. > -- > View this message in context: > http://www.nabble.com/help-to-formulate-problem-in-terms-of-LP-tp16782979p16782979.html > Sent from the Gnu - GLPK - Help mailing list archive at Nabble.com. > > > > > > > _______________________________________________ > Help-glpk mailing list > [email protected] > http://lists.gnu.org/mailman/listinfo/help-glpk -- Psst! Geheimtipp: Online Games kostenlos spielen bei den GMX Free Games! http://games.entertainment.gmx.net/de/entertainment/games/free _______________________________________________ Help-glpk mailing list [email protected] http://lists.gnu.org/mailman/listinfo/help-glpk
