## 5-7 ?‘é??´å?

¨Ï¥Î quiver «ü¥O¥iµe¥X¥­­±¤Wªº¦V¶q³õ¹Ï¡]Quiver Plots¡^¡A¯S§O¾A¥Î©óªí¥Ü¤À¥¬©ó¥­­±ªº¦V¶q³õ ¡]Vector Fields¡^¡A¨Ò¦p¥­­±¤Wªº¹q³õ¤À¥¬¡A©Î¬O¬y³t¤À¥¬¡AÁ|¨Ò¦p¤U¡G

Example 1: 05-¯S®í¹Ï§Î/quiver01.m[x, y, z] = peaks(20); [u, v] = gradient(z); contour(x, y, z, 10); hold on, quiver(x,y,u,v); hold off axis image

¦b¤W¨Ò¤¤¡Agradient ²£¥Í±è«×¦V¶q¡Acontour ¶i¦æµ¥°ª½u§@¹Ï¡A¦Ó quiver «h±N¨C¤@ÂIªº±è«×¦V¶q¥H¤p½b¸¹ªí¥Ü¡C¡]¥Ñ°ò¥»·L¿n¤À¥iª¾¡A±è«×¦V¶q¥Ã»·»Pµ¥°ª½u««ª½¡A¥i¥Ñ¤W¹Ï¦A¦¸±o¨ìÅçÃÒ¡C¡^

Hint
±è«×¦V¶q¤]´N¬O¡u³Ì³t¤U­°ªk¡v¡]Steepest Descent¡^©Ò¦æ¨«¸ô®|ªº¤Ï¤è¦V¡C

Hint
¦b¥»³¹ªº½d¨ÒÀÉ®×¤¤¡Aµ§ªÌ¯S§O·Ç³Æ¤F¤@­Ó¦³½ìªº¤¬°Ê®i¥Ü¡A¥i¥H¦A¤@¦¸ÅçÃÒ±è«×¦V¶q¥Ã»·©Mµ¥°ª½u««ª½¡A½Ð¿é¤J¡ugradientDescentDemo¡v¨Ã¦bµ¥°ª½u¹Ï§Î¤W­±ÂI¿ï·Æ¹«¡A§Y¥iÅã¥Ü³Ì³t¤U­°ªkªº¸ô®|¡C«OÃÒ¦³½ì¡A½Ð¸Õ¸Õ¬Ý¡I

±ýµe¥XªÅ¶¡¤¤ªº¦V¶q³õ¹Ï¡A¥i¥Î quiver3 «ü¥O¡A¦p¤U¡G

Example 2: 05-¯S®í¹Ï§Î/quiver301.m[x, y] = meshgrid(-2:0.2:2, -1:0.1:1); z = x.*exp(-x.^2-y.^2); [u, v, w] = surfnorm(x, y, z); quiver3(x, y, z, u, v, w); hold on, surf(x, y, z); hold off axis equal %colormap('default') % ÃC¦â§ï¦^¹w³]­È

¨ä¤¤ surfnorm ¥i²£¥Í««ª½©ó¦±­±ªºªk¦V¶q¡C

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