someting is wrong but ı didnt find it , I uploaded this question's image

k = 0.16 W/(cm oC)
H = 0.073 W/ (cm2 oC)
Te = 25 oC
Tp = Temperature values of the points on the upper edge.
Q = 27
Δx=Δy=0.5 cm
 perform a direct solution of the problem by using finite differences formulas for the derivatives.

clear all ,close all, clc

Q=27;
delh=0.5;
k=0.16;
H=0.073;
te=298;
w=2;
for i=1:15

A(i)=-(Q*delh^2/(k*w))+30*delh;
A(136-i)=-(Q*delh^2/(k*w))-2*delh*H*te/k;

end
for i=16:120

    A(i)=-(Q*delh*delh/(k*w));
  end
  for i=1:9
      A(15*i)=A(15*i)-20;
      A(15*i-14)=A(15*i-14)-20;
  end
  for i=1:120
      t(i,i)=-4;
  end 
  for i=121:135
  t(i,i)=-4-2*delh*H/k;
  end
  for i=1:134
      t((i+1),i)=1;
      t(i,(i+1))=1;
  end
  for i=1:8
      t((15*i+1),(15*i))=0;
      t((15*i),(15*i+1))=0;
  end 
  for i=1:15
  t(i,(15+i))=2;
  t((136-i),(121-i))=2;
  end  
  for i=16:120
  t(i,(i+15))=1;
  t((136-i),(121-i))=1;
  end
  U=inv(t)*A

[Jan]

We cannot try to solve the problem, when all we know is "something is wrong".

[omer]

thank you, I solved my problem

Answer 1

[Yao Li]

The dimention of Matrix A is 1*135 and the dimention of inv(t) is 135*135. I don't think it's Ok for inv(t)*A. I'm not sure what you really want, but try

U=inv(t)*A'

[omer]

thank your help