I cant find my value for an fsolve.

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Rodrigo Blas
Rodrigo Blas 2020-3-13
评论： Rodrigo Blas 2020-3-13
clc, clear
a1=28*7*400; %%ft^2
po=40.6; %%psi
delpio=9; %%psi
qf=1525; %%gpm
qo=qf;
pp=16.4; %%psi
qp=1234; %%gpm
depr1=24.9; %%psi
delpr2=18.2; %%psi
PH=360; %%ft
lp=2.76*.264/(60)^2*14.5; %%gal/m*min^2/psi
k2=1.75*10^-4*60^1.67*14.5/264.172^1.67; %%psi/(gal/min)^1.67
k3=2.27*10^-2; %%(m^3/h)^.6/m^2
g=32.17; %%ft/s^2
rhoh20=62.4; %%lbs/ft^3
pf=rhoh20*g*PH*1.488*.000145; %%psi
delpo=pf-po; %%psi
icQ=qo;
icdelp=delpo;
%%y=zeros(2,1);
ode=@odes;
xo=[icQ icdelp];
xspan=[0 100];
[X,Y]=ode45(@(x,y)odes(x,y,jw,a1,k2),xspan,xo)
jw=JW(lp,qo,delpio,k3,y,xo,z);
function F=JW(lp,qo,delpio,k3,y,xo,z)
F=fsolve(@findjw,xo);
function F=findjw(z)
F=lp*(y(2)-qo*delpio/y(1)*exp(z/(k3*y(1)^0.40)))-z;
end
end
function dydx=odes(x,y,jw,a1,k2)
%%syms Q(x) P(x)
dydx=zeros(2,1)
dydx(1)=-jw*a1;
dydx(2)=-k2*y(1);
%%dydx1=diff(Q)==-jw*a1;
%%dydx2=diff(P)==-k2*Q;
%%dydx=[-jw*a1;-k2*y(1)];
%%dydx=[dydx1;dydx2]
end
Cannot find an exact (case-sensitive) match for
'jw'
The closest match is: JW in
C:\Users\rodri\AppData\Local\JW.m
Error in mhlro>@(x,y)odes(x,y,jw,a1,k2)
Error in odearguments (line 90)
f0 = feval(ode,t0,y0,args{:}); % ODE15I sets
args{1} to yp0.
Error in ode45 (line 115)
odearguments(FcnHandlesUsed, solver_name, ode,
tspan, y0, options, varargin);
Error in mhlro (line 27)
[X,Y]=ode45(@(x,y)odes(x,y,jw,a1,k2),xspan,xo)
>>
Im trying to find my value for jw which is the answer out of fsolve. This value is dependent on the differential equation function and also within the jw eqution there is a jw which i label as 'z' initially then i change it to jw.
The error i get is above

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回答（1 个）

Cris LaPierre
Cris LaPierre 2020-3-13
You use the variable jw before it gets defined (in your call to ode45). Also, when defining jw, you also use a variable y which has not yet been defined either.
  1 个评论
Rodrigo Blas
Rodrigo Blas 2020-3-13
jw is the answer from JW() fsolve. the JW() function is dependent on the answer from dydx() function.however jw is also a component of the dydx() function.
these two functions have to be computed simultaneously.
I dont know where to start

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