How to use Solver?

Question

Rebecca Reyes 2021-4-13

0
链接

此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/801261-how-to-use-solver

编辑： madhan ravi 2021-4-14

clear  dlc
%feed composition
z1=.5;
z2=.1;
z3=.15;
z4=.25;
 
%other given data
F=150;
PD=250;
T=10;
 
 
 
F=150;
 
%k-values from chart yi/xi
k1=56;
k2=0.65;
k3=0.175;
k4=0.055;
 
%total balances
 
syms x 
eqn=solve(k1*((F*z1)/(k1*x+150-x))+k2*((F*z2)/(k2*x+150-x))+k3*((F*z3)/(k3*x+150-x))+k4*((F*z4)/(k4*x+150-x))==1)
 

I'm trying to solve for x in the eqn but all i get is this:

eqn =
 
                                                                         150
root(z^3 - (151985*z^2)/231 + (2120672000*z)/17787 - 36140000000/5929, z, 1)
root(z^3 - (151985*z^2)/231 + (2120672000*z)/17787 - 36140000000/5929, z, 2)
root(z^3 - (151985*z^2)/231 + (2120672000*z)/17787 - 36140000000/5929, z, 3)

Very confused since I had defined my z constants and I am only looking for the x variable

0 个评论
显示 -2更早的评论隐藏 -2更早的评论

请先登录，再进行评论。

请先登录，再回答此问题。

Answer 1

madhan ravi 2021-4-13

0
链接

此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/801261-how-to-use-solver#answer_674311

Use vpasolve()

6 个评论
显示 4更早的评论隐藏 4更早的评论

Rebecca Reyes 2021-4-13

编辑：Rebecca Reyes 2021-4-13

I see what you are trying to tell me but i see that my approach is all wrong for what i need to get as an answer.

i redid my coding since my answer is supposed to be just one number 88.

I posted it on another post.

Thank you for your help.

madhan ravi 2021-4-14

编辑：madhan ravi 2021-4-14

Wow , you just completely ignored what I told you and simply asked the same question.

%feed composition

z1=.5;

z2=.1;

z3=.15;

z4=.25;

%other given data

F=150;

PD=250;

T=10;

F=150;

%k-values from chart yi/xi

k1=56;

k2=0.65;

k3=0.175;

k4=0.055;

%total balances

syms x

Eqn = k1*((F*z1)/(k1*x+150-x))+k2*((F*z2)/(k2*x+150-x))+k3*((F*z3)/(k3*x+150-x))+k4*((F*z4)/(k4*x+150-x))==1;

X = vpasolve(Eqn) % you can see 4 answers so if you're looking for the root in a certain range say 50 - 100 you can use the below line

X =

X_in_the_range = vpasolve(Eqn, [50 100])

X_in_the_range =

88.652321154384366746951471346875

subs(Eqn, X_in_the_range) % to check if it satisfies, ofcourse it's not an exact solution but a close match to what you're looking for

ans =

Come on , was that hard for you ? The reason I suggested vpasolve() is that you can input the domain for the solver to look for. Please stop asking the same question multiple times just because you didn't understand. It's not encouraged in this forum. Volunteers spend some time in helping and instead of giving them a proper response OP's tend to ask another question simultaneously.

请先登录，再进行评论。