利用matlab編寫S函數(shù)求解微分方程

1、實用文案標準文檔自動化專業(yè)綜合設計報告設計題目：利用matlab編與S函數(shù)求解微分方程所在實驗室：自動化系統(tǒng)仿真實驗室指導教師：郭衛(wèi)平學生姓名律迪迪班級文自 0921學號 200990519114成績評定：_實用文案標準文檔一、設計目的了解使用 simulink 的擴展工具- S-函數(shù)，s 函數(shù)可以利用 matlab 的豐富資源，而不僅僅局限于 simulink 提供的模塊，而用 c 或 C+等語言寫的 s 函數(shù)還可以實現(xiàn)對硬件端口的操 作，還可以操作 windows API 等的，它的魅力在于完美結合了simulink 框圖簡潔明快的特點和編程靈活方便的優(yōu)點，提供了增強和擴展 sin uli

2、 nk能力的強大機制，同時也是使用 RTW實現(xiàn)實時仿真的關鍵。、設計要求求解解微分方程y =y_2x/yy（o）=i要求利用 matlab 編寫 S 函數(shù)求解三、設計內容（可加附頁）【步驟 1】獲取狀態(tài)空間表達式。在 matlab 中輸入dsolve( Dy=y-2*x/y , y(0)=1；x)得到y(tǒng)=(2*x+1).A(1/2);【步驟 2】建立 s 函數(shù)的 m 文件。利用 21 用 S 函數(shù)模板文件。 以下是修改之后的模板文件 sfun tmpl.m 的內容。function sys,xO,str,ts = sfun tmpl(t,x,u,flag)%SFUNTMPL General M

3、-file S-fu nctio n template% With M-file S-functions, you can defi ne you own ordinary differe ntial% equati ons (ODEs), discrete system equati ons, an d/or just about% any type of algorithm to be used within a Simulink block diagram.% The gen eral form of an M-File S-fu nctio n syntax is:% SYS,XO,S

4、TR,TS = SFUNC(T,X,U,FLAG,P1,.,P n)% What is retur ned by SFUNC at a give n point in time, T, depe nds on the% value of the FLAG, the curre nt state vector, X, and the curre nt% in put vector, U.% FLAG RESULTDESCRIPTION% _ _ _% 0 SIZES,XO,STR,TS In itializatio n, return system sizes in SYS,實用文案標準文檔%i

5、n itial state in X0, state orderi ng stri ngs%in STR, and sample times in TS.%1DXReturn continuous state derivatives in SYS.%2DSUpdate discrete states SYS = X(n+1)% 3YRetur n outputs in SYS.% 4TNEXTReturn next time hit for variable step sample%time in SYS.% 5Reserved for future (root findin g).% 9Te

6、rmi natio n, perform any clea nup SYS=.% The state vectors, X and X0 con sists of con ti nu ous states followed% by discrete states.% Opti onal parameters, P1,.,P n can be provided to the S-function and% used duri ng any FLAG operati on.% When SFUNC is called with FLAG = 0, the followi ng in formati

7、o n% should be retur ned:% SYS(1) = Number of contin uous states.% SYS(2) = Number of discrete states.% SYS(3) = Number of outputs.% SYS(4) = Number of in puts.%Any of the first four eleme nts in SYS can be specified%as -1 in dicat ing that they are dyn amically sized. The%actual le ngth for all oth

8、er flags will be equal to the%len gth of the in put, U.% SYS(5) = Reserved for root finding. Must be zero.% SYS(6) = Direct feedthrough flag(仁yes, 0=n o). The s-fu ncti on%has direct feedthrough if U is used duri ng the FLAG=3%call. Setting this to 0 is akin to making a promise that%U will not be us

9、ed duri ng FLAG=3. If you break the promise%the n un predictable results will occur.% SYS(7) = Number of sample times. This is the nu mber of rows in TS.% X0= In itial state con diti ons or if no states.% STR = State orderi ng stri ngs which is gen erally specified as .% TS = An m-by-2 matrix containing the sample time%(period, offset) in formati on. Where m = nu mber of sample%times. The orderi ng of the sample times must be:%實用文案標準文檔%TS = 00,: Continu ous sample time.%01,: Continu ous, but fixed in minor step%sample time.%PERIOD OF