[討論] 找出兩條直線的交點

看板MATLAB作者middle1023 (米豆)時間17年前 (2007/04/12 18:53)推噓5(5推 0噓 0→)

留言5則, 4人參與討論串1/1

小弟因為有需要可是爬過文發現沒有人有這樣的問題於是自己寫了一個也順便分享出來希望各位前輩也可以幫小弟找看看有沒有錯誤還是說有更好的寫法以下是code function [x y] = crosspoint(line1,line2) % This function can find the cross point with two straight lines % Input matrix : line1 = [line1(x1),line1(y1) ; line1(x2),line1(y2)] % line2 = [line2(x1),line2(y1) ; line2(x2),line2(y2)] % x1,y1 and x2,y2 is the two end points of lines % [x y] is the cross point of two straight lines %%%%%%% test %%%%%%%% line1 = [0.8,2.6 ; 6,9.4]; line2 = [5,-2 ; 2.55,8.45]; %%%%%%% test %%%%%%%% x11 = line1(1,1); y11 = line1(1,2); x21 = line1(2,1); y21 = line1(2,2); x12 = line2(1,1); y12 = line2(1,2); x22 = line2(2,1); y22 = line2(2,2); %%%%%%% test %%%%%%%% plot([x11 x21] ,[y11 y21]);hold on;plot([x12 x22] ,[y12 y22]); %%%%%%% test %%%%%%%% seta = 0; setb = 0; % line1 if x11 == x21 % for x = a y + b str1 = [num2str(x11) '=a*(' num2str(y11) ')+b']; str2 = [num2str(x21) '=a*(' num2str(y21) ')+b']; [aa1,bb1] = solve(str1,str2,'a','b'); a1 = subs(aa1) ; b1 = subs(bb1) ; seta = 1; else % y11 == y21 or other % for y = a x + b str1 = [num2str(y11) '=a*(' num2str(x11) ')+b']; str2 = [num2str(y21) '=a*(' num2str(x21) ')+b']; [aa1,bb1] = solve(str1,str2,'a','b'); a1 = subs(aa1) ; b1 = subs(bb1) ; end % line2 if x12 == x22 % for x = a y + b str1 = [num2str(x12) '=a*(' num2str(y12) ')+b']; str2 = [num2str(x22) '=a*(' num2str(y22) ')+b']; [aa2,bb2] = solve(str1,str2,'a','b'); a2 = subs(aa2) ; b2 = subs(bb2) ; setb = 1; else % y12 == y22 or other % for y = a x + b str1 = [num2str(y12) '=a*(' num2str(x12) ')+b']; str2 = [num2str(y22) '=a*(' num2str(x22) ')+b']; [aa2,bb2] = solve(str1,str2,'a','b'); a2 = subs(aa2) ; b2 = subs(bb2) ; end % solve y = a*x + b if seta == 1 st1 = ['x=' num2str(a1) '*y+(' num2str(b1) ')']; else st1 = ['y=' num2str(a1) '*x+(' num2str(b1) ')']; end if setb == 1 st2 = ['x=' num2str(a2) '*y+(' num2str(b2) ')']; else st2 = ['y=' num2str(a2) '*x+(' num2str(b2) ')']; end [xx,yy] = solve(st1,st2,'x','y'); x = subs(xx); y = subs(yy); %%%%%%% test %%%%%%%% plot(x,y,'o','MarkerSize',3,'LineWidth',2); %%%%%%% test %%%%%%%% % program end 謝謝大家 -- ※ 發信站: 批踢踢實業坊(ptt.cc) ◆ From: 140.116.71.95