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津津愛睡覺金蟲 (小有名氣)
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[求助]
Matlab小白,急需計算一個模型,求懂的大神看看怎么修改。萬分感謝 已有2人參與
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Matlab小白,急需計算一個模型,解微分方程組,求懂的大神看看怎么修改。萬分感謝 function dy = funct(t,y) I = 50 % mA F = 96487 % C/mol c0 = 10 % mM Vol = 3.344 % ml Q = 6.5 % ml/min A = 33.75 % cm2 syms x eqn = 0.86*x+0.4*(x*exp(-asinh(theta/(-2*x)))+x*exp(asinh(theta/(-2*x))))==y(3) cma = double(solve(eqn,x)) cmion = (y(3)-0.86*cma)/0.4 phi_sp = asinh(-3/y(2)) phi_ele = asinh(-3/cma) phi_mem = (I*170)/(-1.12*F*(cma.*cosh(phi_ele)+y(2).*cosh(phi_sp))) J = -(1.12*1e-3/170)*(2*cma.*cosh(phi_ele)-2*y(2).*cosh(phi_sp))+3*phi_mem dy=zeros(3,1); dy(1) = (1e4*I/A)/(116*F) dy(2) = -J/(250e-6*0.5)+(c0-y(2))/(0.5*(Vol/Q)*60) dy(3) = J/(290*1e-6) end clear all; c0=10 tspan=[0 600] [t,y] = ode45(@funct,tspan,[0 c0 1.66*c0]) plot(t, y(:,2)) xlabel('t'),ylabel('c') 錯誤使用 odearguments (line 92) FUNCT 返回的矢量的長度為 2,但初始條件矢量的長度為 3。FUNCT 返回的矢量和初始條件矢量的元素數(shù)目必須相同。 出錯 ode45 (line 113) [neq, tspan, ntspan, next, t0, tfinal, tdir, y0, f0, odeArgs, odeFcn, ... |

金蟲 (小有名氣)
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dy(1)=a*y(1)+b*y(2); y(2)=c*y(1)+d*y(3); dy(3)=-e*y(2)*(y(3)-t)/y(1); function daedi a=-0.2; b=0.5; c=0.1; d=-1; e=0.3; y0=[0.8;0.5;0.1]; %初值,y0(2)=0.5是猜測值 options=optimset('display','off'); y0(2)=fsolve(@(y2)y2-(c*y0(1)+d*y0(3)),y0(2),options); %求出相容的初值y0(2) % 求解微分方程 [t,y]=ode45(@(t,y)myodefun(t,y,a,b,c,d,e),[0,20],y0); figure('numbertitle','off','name','DAE 求解示例 方法1.2') plot(t,y) legend('y1(t)','y2(t)','y3(t)') function dy=myodefun(t,y,a,b,c,d,e) dy=zeros(3,1); % dy(2)=0很重要,否則反求出y(2)后會被積分 % 先求解代數(shù)方程,順序很重要 cons=@(y2)y2-(c*y(1)+d*y(3)); % 隱式代數(shù)約束 options=optimset('display','off'); % 關(guān)閉提示 y(2)=fsolve(cons,y(2),options); %用上次的y(2)作為猜測值 dy(1)=a*y(1)+b*y(2); dy(3)=-e*y(2)*(y(3)-t)/y(1); 現(xiàn)在通過這個例子已經(jīng)可以運行,想問您怎么繼續(xù)編寫這個例子中y(2)隨t的動態(tài)變化呢 感謝感謝 |

鐵蟲 (小有名氣)

金蟲 (小有名氣)
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function dydt = funct(t,x, y) I = 50; % mA F = 96487; % C/mol c0 = 10; % mM Vol = 3.344; % ml Q = 6.5; % ml/min A = 33.75; % cm2 y1=y(1); y2=y(2); y3=y(3); y3 = 0.86*x+0.4*(x*exp(-asinh(y1/(-2*x)))+x*exp(asinh(y1/(-2*x)))) phi_sp = asinh(-3/y2) phi_ele = asinh(-3/x) phi_mem=(I*170)/(-1.12*F*(x*cosh(phi_ele)+y2*cosh(phi_sp))) J =-(1.12*1e-3/170)*(2*x*cosh(phi_ele)-2*y2*cosh(phi_sp))+3*phi_mem dy1dt = (1e4*I/A)/(116*F) dy2dt = -J/(250e-6*0.5)+(c0-y2)/(0.5*(Vol/Q)*60) dy3dt = J/(290*1e-6) end clear all; I = 50; % mA F = 96487; % C/mol c0 = 10; % mM Vol = 3.344; % ml Q = 6.5; % ml/min A = 33.75; % cm2 tspan=[0 600] x0=c0 [t,x,y] = ode45(@funct,tspan, c0, [0 c0 1.66*c0]) plot(t, theta) xlabel('t'),ylabel('c') 出錯 ode45 (line 113) [neq, tspan, ntspan, next, t0, tfinal, tdir, y0, f0, odeArgs, odeFcn, ... 改了程序,現(xiàn)在錯誤變成這樣。公式就是想解一個三個未知數(shù)的微分方程組,但是里面有未知數(shù) |

金蟲 (小有名氣)
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function dydt = funct(t,x, y) I = 50; % mA F = 96487; % C/mol c0 = 10; % mM Vol = 3.344; % ml Q = 6.5; % ml/min A = 33.75; % cm2 y1=y(1); y2=y(2); y3=y(3); y3 = 0.86*x+0.4*(x*exp(-asinh(y1/(-2*x)))+x*exp(asinh(y1/(-2*x)))) phi_sp = asinh(-3/y2) phi_ele = asinh(-3/x) phi_mem=(I*170)/(-1.12*F*(x*cosh(phi_ele)+y2*cosh(phi_sp))) J =-(1.12*1e-3/170)*(2*x*cosh(phi_ele)-2*y2*cosh(phi_sp))+3*phi_mem dy1dt = (1e4*I/A)/(116*F) dy2dt = -J/(250e-6*0.5)+(c0-y2)/(0.5*(Vol/Q)*60) dy3dt = J/(290*1e-6) end clear all; I = 50; % mA F = 96487; % C/mol c0 = 10; % mM Vol = 3.344; % ml Q = 6.5; % ml/min A = 33.75; % cm2 tspan=[0 600] x0=c0 [t,x,y] = ode45(@funct,tspan, c0, [0 c0 1.66*c0]) plot(t, theta) xlabel('t'),ylabel('c') 出錯 ode45 (line 113) [neq, tspan, ntspan, next, t0, tfinal, tdir, y0, f0, odeArgs, odeFcn, ... 改了程序,現(xiàn)在錯誤變成這樣。公式就是想解一個三個未知數(shù)的微分方程組,但是里面有未知數(shù) |

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