How to solve 2 equations with 2 unknown variables and plot the result?

조회 수: 3(최근 30일)
Nabilla Dewi Septiani
Nabilla Dewi Septiani 2021년 12월 6일
댓글: Nabilla Dewi Septiani 2021년 12월 9일
I have this code to solve 2 equations with 2 unknown variables. And there are 2 known variables that is in a range. It gives the result but only one, where I expect it to be in a range too. Also, I could not plot it.
%Parameters
xin=0.2; xout=0.1; Pr=0.3; qf=1;
x=0:0.1:1;
alpha=0:100:1000;
%For Cross-Flow Module (CF)
y=(1+(x+Pr).*(alpha-1))-((1+(x+Pr).*(alpha-1)).^2-(4.*alpha.*(alpha-1).*x.*Pr)).^0.5/(2.*Pr.*(alpha-1))
y = 1×11
1.0e+03 * -0.0001 0.0398 0.0997 0.1796 0.2795 0.3994 0.5393 0.6992 0.8791 1.0790 1.2989
%qfout-qf=-(1-Pr+((alpha-1).*(x-Pr.*y)))*a
%x-xin=(-(1/qf).*(alpha.*(x-(Pr.*y))*a)+(-x.*ln(qfout/qf))
syms a qfout
E=-(1-Pr+((alpha-1).*(x-Pr.*y)))*a==qfout-qf , (-(1/qf).*alpha.*(x-(Pr.*y))*a)+(-x.*log(qfout/qf))==x-xin;
E = 
S=solve(E,a,qfout)
S = struct with fields:
a: 0 qfout: 1
plot(alpha,a)
Error using plot
Data must be numeric, datetime, duration or an array convertible to double.

채택된 답변

KSSV
KSSV 2021년 12월 6일
You need to convert the sym class to double using double.
plot(double(alpha),double(E))
  댓글 수: 1
Nabilla Dewi Septiani
Nabilla Dewi Septiani 2021년 12월 9일
Thank you sir. I can plot it now
But how to get the value for each array? As I only got one result and it is zero

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