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[求助]
matlab擬合方程參數(shù)時初值的選擇
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A+B=C A+W=R R+B=C+W 先考慮的三個反應(yīng)都是可逆反應(yīng),有以下幾個式子:編寫程序如下 %30℃ clear all clc global keq1 keq2 t0 c0 keq1 = 3.94; % 平衡常數(shù)k1 keq3 = 1.08; % 平衡常數(shù)k3 t0 = [5,10, 15, 30, 45, 60,90,120,160,200,240,300,360]; c0 = [5.939601,5.203973,0,0.022484,0.078956] % A B C R W 組成的初始濃度 ci=[3.742508811 4.213566482 0.990406938 0.252498405 0.090415512; 3.045716838 3.387013322 1.816960097 0.215546741 0.081072022; 2.504754523 2.901991595 2.301981824 0.193427102 0.099462604; 1.65098702 2.036686653 3.167286766 0.170236582 0.095144044; 1.271633833 1.655460403 3.548513016 0.124730781 0.10334349; 1.129887499 1.630815394 3.573158025 0.129798695 0.097764543; 1.01239208 1.460748979 3.74322444 0.144649391 0.073614958; 1.007417603 1.429180292 3.774793127 0.123477124 0.094249307; 0.990005723 1.499216939 3.704756481 0.135524067 0.076072022; 0.970073726 1.493966669 3.71000675 0.130791851 0.076387812; 0.96903024 1.429705429 3.77426799 0.119510017 0.101202216; 0.980873385 1.457988124 3.745985296 0.124189274 0.097022161; 0.98477262 1.453402965 3.750570455 0.1200936 0.0762608]; % cA cC cR 對應(yīng)時間數(shù)值 k0=[1 1 1]; % k1+, k2, k3+ 初始向值 lb = [0 0 0]; ub = [1000 1000 500]; % 上下限 % 使用函數(shù)lsqnonlin()進行參數(shù)估計 [k,resnorm,residual,exitflag] = lsqnonlin(@ObjFunc,k0,lb,ub,[],ci); k1plus=k(1); k1minus= k1plus/keq1; k2=k(2); k3plus=k(3); k3minus= k3plus/keq3; % ------------------------------------------------------------------ function f = ObjFunc(k,ci) % 目標函數(shù) global t0 c0 [t,c_cal] = ode45(@Euqations,t0,c0,[],k); f= sum((c_cal-ci)^2); % ------------------------------------------------------------------ function dcdt = Euqations(t,c,k) global keq1 keq2 k1plus=k(1); k1minus= k1plus/keq1; k2=k(2); k3plus=k(3); k3minus= k3plus/keq3; cA=c(:,1); cB=c(:,2); cC=c(:,3); cR=c(:,4); cW=c(:,5); dcAdt = k1plus*cA*cB-k1minus*cC+k2*cA*cW; dcCdt = -k1plus*cA*cB+k1minus*cC+k3plus*cB*cR-k3minus*cC*cW; dcRdt = k2*cA*cW-k3plus*cB*cR+k3minus*cC*cW; dcdt = [dcAdt; dcCdt;dcRdt]; 但是k的初值一直影響結(jié)果,程序要怎么改一下初值對結(jié)果影響不大(這個程序有問題,) |
鐵桿木蟲 (職業(yè)作家)
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我寫在附件里面了 |
鐵桿木蟲 (職業(yè)作家)
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不好意思,我的微分方程組就是附件里面標(1)(2)(3)的三個式子,對應(yīng)的數(shù)據(jù)為 時間:t0 = [5,10, 15, 30, 45, 60,90,120,160,200,240,300,360]; 不同時刻對應(yīng)的數(shù)據(jù) c0 = [5.939601,5.203973,0,0.022484,0.078956] % A B C R W 組成的初始濃度 ci=[3.742508811 4.213566482 0.990406938 0.252498405 0.090415512; 3.045716838 3.387013322 1.816960097 0.215546741 0.081072022; 2.504754523 2.901991595 2.301981824 0.193427102 0.099462604; 1.65098702 2.036686653 3.167286766 0.170236582 0.095144044; 1.271633833 1.655460403 3.548513016 0.124730781 0.10334349; 1.129887499 1.630815394 3.573158025 0.129798695 0.097764543; 1.01239208 1.460748979 3.74322444 0.144649391 0.073614958; 1.007417603 1.429180292 3.774793127 0.123477124 0.094249307; 0.990005723 1.499216939 3.704756481 0.135524067 0.076072022; 0.970073726 1.493966669 3.71000675 0.130791851 0.076387812; 0.96903024 1.429705429 3.77426799 0.119510017 0.101202216; 0.980873385 1.457988124 3.745985296 0.124189274 0.097022161; 0.98477262 1.453402965 3.750570455 0.1200936 0.0762608]; 要求的是ki+,k2,k3+, 另外方程中的ki-=ki+/3.14,k3-=k3+/1.08 |
鐵桿木蟲 (職業(yè)作家)
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有的,我寫在附件里了,真是太謝謝了 |
鐵桿木蟲 (職業(yè)作家)
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dCB/wdt"應(yīng)該是“dCB/dt,沒錯 對不起我太心急了,公式已經(jīng)檢查過,我保證這次沒錯了,真的 |
鐵桿木蟲 (職業(yè)作家)
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