11-3 ODE ���������������

©Ò¦³ªº ODE «ü¥O¥i¥H±µ¨ü²Ä¥|­Ó¿é¤JÅܼơA¥Nªí¿n¤À¹Lµ{¥Î¨ìªº¦UºØ¿ï¶µ¡]Options¡^¡A¦¹ºØ ODE «ü¥Oªº®æ¦¡¬°¡G

[t, y] = solver('odeFile', [t0, tn], y0, options);

¨ä¤¤ options ¬O¥Ñ odeset «ü¥O¨Ó±±¨îªºµ²ºcÅܼơA¦¹µ²ºcÅܼƧY¥]§t¤F¿n¤À¹Lµ{¥Î¨ìªº¦UºØ¿ï¶µ¡Aodeset ªº¤@¯ë®æ¦¡¦p¤U¡G

options = odeset('name1', value1, 'name2', value2, ¡K)

¦¹®É²£¥Íªºµ²ºcÅÜ¼Æ options¡A¨äÄæ¦ì name1 ªº­È¬° value1¡AÄæ¦ì name2 ªº­È¬° value2¡A¨Ì¦¹Ãþ±À¡C¥¼³Q³]©wªºÄæ¦ì¡A¨äÄæ¦ì­È§Y¬°¹w³]­È¡C

§Ú­Ì¤]¥i¥H¥u§ïÅܤ@­Ó²{¦sªº options µ²ºcÅܼƤ¤¡A¬Y­ÓÄæ¦ìªº­È¡A¨ä®æ¦¡¦p¤U¡G

newOptions = odeset(options, 'name', value);

­Y­nŪ¥X¬Y­ÓÄæ¦ìªº­È¡A¥i¥Î odeget¡A¨ä®æ¦¡¦p¤U¡G

value = odeget(otpions, 'name');

¨ä¤¤ name ¬°Äæ¦ì¦WºÙ¡Avalue §Y¬°¹ïÀ³ªºÄæ¦ì­È¡C

·í¨Ï¥Î odeset «ü¥O®É¡A­YµL¥ô¦ó¿é¤JÅܼơA«h odeset ·|Åã¥Ü©Ò¦³ªºÄæ¦ì¦WºÙ¤ÎÄæ¦ì­È¡A¨Ã¥H¤j¬A¸¹¥Nªí¹w³]­È¡A¨Ò¦p¡G

Example 1: 11-±`·L¤À¤èµ{¦¡/odeset01.modeset AbsTol: [ positive scalar or vector {1e-6} ] RelTol: [ positive scalar {1e-3} ] NormControl: [ on | {off} ] NonNegative: [ vector of integers ] OutputFcn: [ function_handle ] OutputSel: [ vector of integers ] Refine: [ positive integer ] Stats: [ on | {off} ] InitialStep: [ positive scalar ] MaxStep: [ positive scalar ] BDF: [ on | {off} ] MaxOrder: [ 1 | 2 | 3 | 4 | {5} ] Jacobian: [ matrix | function_handle ] JPattern: [ sparse matrix ] Vectorized: [ on | {off} ] Mass: [ matrix | function_handle ] MStateDependence: [ none | {weak} | strong ] MvPattern: [ sparse matrix ] MassSingular: [ yes | no | {maybe} ] InitialSlope: [ vector ] Events: [ function_handle ]

³o¨ÇÄæ¦ì¦WºÙ¤Î¬ÛÃö»¡©ú¡A¥i¨£¤Uªí¡G

Ãþ§OÄæ¦ì¦WºÙ¸ê®Æ«¬ºA¹w³]­È»¡©ú
»~®t®e§Ô«×¤§¬ÛÃöÄæ¦ìRelTol¥¿¯Â¶q$10^{-3}$¬Û¹ï»~®t®e§Ô«×
AbsTo1¥¿¯Â¶q©Î¦V¶q$10^{-6}$µ´¹ï»~®t®e§Ô«×
¿n¤À¿é¥X¤§¬ÛÃöÄæ©ÊOutPutFcn¦r¦ê'odeplot'¿é¥X¨ç¦¡¡]­Y ODE «ü¥OµL¿é¥XÅܼơA«h¦b¼Æ­È¿n¤À°õ¦æ§¹²¦«á¡AMATLAB ·|©I¥s¦¹¿é¥X¨ç¦¡¡^
OutputSel¯Á¤Þ¦V¶q¥þ³¡ODE «ü¥O¤§¿é¥XÅܼƪº¯Á¤Þ­È¡A¥H¨M©w¨º¨Ç¿é¥XÅܼƤ§¤¸¯À±N³Q°e¨ì¿é¥X¨ç¦¡
Refine¥¿¾ã¼Æ1©Î4 (for ode45)Refine = 2 ¥i²£¥Í¨â­¿¼Æ¶qªº¿é¥XÂI¡ARefine = 3 ¥i²£¥Í¤T­¿¼Æ¶qªº¿é¥XÂI¡A¨Ì¦¹Ãþ±À¡C
Statson ©Î offoffStats = 'on' ²£¥Í­pºâ¹Lµ{ªº¦UºØ²Î­p¸ê®Æ¡C
Jacobian ¯x°}¤§¬ÛÃöÄæ¦ìJconstanton ©Î offoff¦pªG Jacobian ¯x°}±`¼Æ¡A«h Jconstant = 'on'
Jacobianon ©Î offoff­YF(t, y, 'Jacobian') ¶Ç¦^ $\partial F/\partial y$¡A«h Jacobian = 'on'
Jpatternon ©Î offoff­Y F([ ], [ ], 'JPattern') ¶Ç¦^ $\partial F/\partial y$¡A¥B $\partial F/\partial y$ ¬Oµ}²¨¯x°}¡A«h Jpattem = 'on'
Vectorizedon ©Î offoff­Y F(t, [y1, y2¡K..]) ¶Ç¦^ [F(t,y1), F(t,y2)¡K..]¡A«h Vectorized = 'on'
¿n¤À¨Bªø¡]Step Sizes¡^¤§¬ÛÃöÄæ¦ìMax Step¥¿¯Â¶q ODE «ü¥O¤§¿n¤À¨Bªø ªº¤W­­
Initial Step¥¿¯Â¶q °_©l¨Bªøªº«ØÄ³­È
½è¶q¯x°}¤§¬ÛÃöÄæ¦ìMassnone¡AM¡AM(t)¡A©Î M(t, y)noneªí©ú ODE «ü¥O®×¬O§_·|¶Ç¦^½è¶q¯x°}
MassSingularyes¡Ano ©Î maybemaybeªí©ú½è¶q¯x°}¬O§_¬° Singular
¨Æ¥óµo¥Í®É¶¡¤§¬ÛÃöÄæ¦ìEventson ©Î offoff­Y ODE ÀɮרöǦ^¨Æ¥ó¨ç¦¡¤Î¬ÛÃö¸ê°T¡A«h Events = 'on'
Ode15s ¤§¬ÛÃöÄæ¦ìMaxOrder1, 2, 3, 4 ©Î 55¿n¤À¤½¦¡¥Î¨ìªº³Ì°ª¦¸¼Æ
BDFon ©Î offoff­Y¨Ï¥Î BDF¡]Backward Differentiation Formula¡^«h BDF = 'on'

¥H¤U¹ï´X­Ó±`¥Î¨ìªºÄæ¦ì¨Ó¶i¦æ»¡©ú¡C

f ¦b¿n¤À»~®t®e§Ô«×¤è­±¡A¨C¤@¦¸¿n¤À©Ò²£¥Íªº§½³¡»~®t e(i)¡A¥²¶·º¡¨¬¤U¦C¤èµ{¦¡¡G

$$ |e(i)| \leq max(RelTol*|y(i)|, AbsTol(i)) $$

¨ä¤¤ i ¥Nªí²Ä i ­Óª¬ºAÅܼơA¦]¦¹¡A§Ú­Ì¥i­°§C RelTol ¤Î AbsTol ¨Ó¨D±o§óºë½Tªº¿n¤Àµ²ªG¡C¨Ò¦p¡G

Example 2: 11-±`·L¤À¤èµ{¦¡/odeRelTol01.msubplot(2,1,1); ode45('vdp1', [0 25], [3 3]'); title('RelTol=0.01'); options = odeset('RelTol', 0.00001); subplot(2,1,2); ode45('vdp1', [0 25], [3 3]', options); title('RelTol=0.0001');

¦b¤W­z½d¨Ò¤¤¡A²Ä¤@­Ó¹Ï©Ò¨Ï¥Îªº¬Û¹ï»~®t­È¬O0.01¡]¹w³]­È¡^¡A²Ä¤G­Ó¹Ï©Ò¨Ï¥Îªº¬Û¹ï»~®t­È¬O0.00001¡A¦]¦¹§Ú­Ì±o¨ì¸û²Ó±KªºÂI¡A¦ý©Òªáªº­pºâ®É¶¡¤]·|¤ñ¸ûªø¡C

¦b¿n¤À¿é¥Xªº¬ÛÃö³B²z¤è­±¡A§Ú­Ì¥i¥H¿ï¥Î¤@­Ó OutputFcn¡A¨Ï±o·í ODE «ü¥O¨S¦³¿é¥XÅܼƮɡA¦¹¿é¥X¨ç¦¡ OutputFcn ·|³Q MATLAB ©I¥s¡COutputFcn ªº¹w³]­È¬O¡¨odeplot¡¨¡A¨ä¥\¯à¬°µe¥X©Ò¦³ªºª¬ºAÅܼơA¨ä¥¦¥i¥Îªº¨ç¦¡ÁÙ¦³¡G

¥H Lorenz ´ý¨P¤èµ{¦¡¡]Lorenz Chaotic Equation¡^¬°¨Ò¡A¨ä ODE Àɮפ§¤º®e¥iÅã¥Ü¦p¤U¡G

11-±`·L¤À¤èµ{¦¡/lorenzOde.mfunction dy = lorenzOde(t, y) % LORENZODE: ODE file for Lorenz chaotic equation SIGMA = 10.; RHO = 28; BETA = 8./3.; A = [ -BETA 0 y(2) 0 -SIGMA SIGMA -y(2) RHO -1 ]; dy = A*y;

±ý¨Ï¥Î ode45 ¹ï¤W­zLorenz ´ý¨P¤èµ{¦¡¶i¦æ¼Æ­È¿n¤À¡A¥i¨£¦¹½d¨Ò¡G

Example 3: 11-±`·L¤À¤èµ{¦¡/odeLorenz01.mode45('lorenzOde', [0 10], [20 5 -5]');

½Ðª`·N¦b¤W¦C¹Ï¤¤¡A¦@¦³¤T±ø¦±½u¡A¥Nªí¤T­Óª¬ºAÅܼÆÀH®É¶¡Åܤƪº¹Ï§Î¡C­Y­nµe¤T«×ªÅ¶¡¤§¬Û¦ì¹Ï§Î¡A¥i¨Ï¥Î¤U¦C½d¨Ò¡G

Example 4: 11-±`·L¤À¤èµ{¦¡/odeLorenz02.moptions = odeset('OutputFcn', 'odephas3'); % ¨Ï¥Î odephas3 ¶i¦æÃ¸¹Ï ode45('lorenzOde', [0 10], [20 5 -5]', options);

¤W­z¹Ï§Î¤¤¥u¥X²{¤@±ø¦±½u¡A¦¹¦±½u¥Nªí¥H¤T­Óª¬ºAÅܼƬ°®y¼Ð¡B¥H®É¶¡¬°°Ñ¼Æªº¤@±ø¤T«×ªÅ¶¡¤¤ªº¦±½u¡C

Hint
­Y­nÆ[¬Ý Lorenz ´ý¨P¤èµ{¦¡ÀH®É¶¡¦ÓÅܪº°Êµe¡A¥i¦b MATLAB «ü¥Oµøµ¡¤Uª½±µ¿é¤Jlorenz «ü¥O§Y¥i¡C«D±`¦³½ì¡A­È±o¤@¬Ý¡I

¤@¯ë¦Ó¨¥¡A°²³]§Ú­Ìªº OutputFcn ³]¦¨"myFunc"¡G

options = odeset('OutputFcn', 'myFunc')

«h¦b¾ã­Ó¿n¤À¹Lµ{¤¤¡AmyFunc ³Q©I¥sªº±¡ªp¦p¤U¡G

  1. ¿n¤À¶}©l®É¡AODE «ü¥O·|©I¥s myFunc(tspan, y0, 'init') ¥HÅý myFunc ¶i¦æ¦UºØªì©l¤Æ°Ê§@¡C
  2. ¦b¨C­Ó¿n¤À¨BÆJ¤¤¡AODE «ü¥O±N·|«ùÄò©I¥s status=myFunc(t, y)¡A­Y status=1¡A«h°±¤î¿n¤À¡C
  3. ¦b¿n¤Àµ²§ô®É¡AODE «ü¥O·|©I¥s myFunc([], [], 'done')¡A¥HÅý myFunc ¶i¦æ¦¬§À°Ê§@¡C
¦]¦¹¡A­Y§Ú­Ì­n¦b¿n¤À¹Lµ{¤¤²£¥Í°Êµe¡A´N¥i¥H®Ú¾Ú¤W­z­ì«h¨Ó³]­p myFunc.m¡C

OutputSel ¥i«ü©w­n¶Ç°e¨ì OutputFcn ªºª¬ºAÅܼƤ§¤¸¯À¡C¨Ò¦p¡A­Y¥u­n¶Ç°e²Ä¤@¤Î²Ä¤T­Ó Lorenz ´ý¨P¤èµ{¦¡ªºª¬ºAÅÊ¼Æ¦Ü odeplot¡A¥i¿é¤J¦p¤U¡G

Example 5: 11-±`·L¤À¤èµ{¦¡/odeOutputSelect01.moptions = odeset('OutputSel', [1,3]); % ¥uµe¥X²Ä¤@©M²Ä¤T­Óª¬ºAÅÜ¼Æ ode45('lorenzOde', [0 10], [20 5 -5]', options);

¦b¤W¹Ï¤¤¡A§Ú­Ì¥uµe¥X¤F²Ä¤@©M²Ä¤T­Óª¬ºAÅܼơC

Refine Äæ¦ì¥i¥H¨Ï¥Î¤º´¡ªk¨Ó¼W¥[¿é¥Xª¬ºAÅܼƪº±K«×¡A¥H±o¨ì¸û¥­·Æªº¿é¥X¦±½u¡C¦b¤U¨Ò¤¤¡A§Ú­Ì§Q¥Î Refine Äæ¦ì¨Ó¨Ï ode23 ªº¿é¥XÂI­Ó¼Æ¼W¬°­ì¥ýªº¤T­¿¡G

Example 6: 11-±`·L¤À¤èµ{¦¡/odeRefine01.msubplot(2,1,1); ode23('vdp1', [0 25], [3 3]'); subplot(2,1,2); options = odeset('Refine', 3); ode23('vdp1', [0 25], [3 3]', options);

·í Stat=on ®É¡AODE «ü¥O·|¦b°õ¦æ§¹²¦«áÅã¥Ü­pºâ¹Lµ{ªº¦UºØ²Î­p¼Æ¦r¡A¨Ò¦p¡G

Example 7: 11-±`·L¤À¤èµ{¦¡/odeShowStats01.m[t, y] = ode45('vdp1', [0 25], [3 3]', odeset('Stat', 'on'));71 successful steps 10 failed attempts 487 function evaluations

¬Û¦Pªº²Î­p¼Æ¦r¡A¤]¥i¥Ñ ODE «ü¥Oªº²Ä¤T­Ó¿é¥XÅܼƶǦ^¡A¨Ò¦p¡G

Example 8: 11-±`·L¤À¤èµ{¦¡/odeShowStats02.m[t, y, s] = ode45('vdp1', [0 25], [3 3]'); ss = 71 10 487 0 0 0

MaxStep ¤Î InitialStep Äæ¦ì¥i¥Î¨Ó½Õ¾ã³Ì¤j¿n¤À¨Bªø¤Î°_©l¿n¤À¨Bªø¡C¦ý¤@¯ë¦Ó¨¥¡A±z¤£¥²¥h½Õ¾ã³o¨â­Ó¼Æ­È¡A¦]¬° ODE «ü¥O¥»¨­´N¨ã¦³¨Bªø¦Û°Ê½Õ¾A¥\¯à¡C¯S§O­È±oª`·Nªº¬O¡G

¨ä¥¦Äæ¦ì¦]¸û¤Ö¥Î¨ì¡A¤£¦AÂØ­z¡A¦³¿³½ìªºÅªªÌ¡A¥iª½±µÂ½¾\ MATLAB ¦³Ãö ODE ªº¤â¥U¡C


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