# Gauss seidel in VBA

Trying to use Gauss seidel method to solve a 25 by 25 matrix to solve a 2D heat transfer chemical engineering problem.

But it doesnt go to 2nd iteration

``````Do While error > 0.1

temps0 = temps1(UBound(matrix1, 1), 1) ' Old temperature for error calculation

'Conducts the gauss algorithm for each row
For i = 1 To UBound(matrix1, 1)
temps1(i, 1) = matrix1(i, UBound(matrix1, 2))
For j = 1 To (UBound(matrix1, 2) - 1)
If j <> i Then
temps1(i, 1) = temps1(i, 1) - (matrix1(i, j) * temps1(j, 1))
ElseIf j = i Then
divider = matrix1(i, j)
End If
Next j
temps1(i, 1) = temps1(i, 1) / divider
Next i

error = Abs((temps1(UBound(matrix1, 1), 1) - temps0) / temps1(UBound(matrix1,     1), 1))
iteration = iteration + 1

Loop
``````

this is the do while loop for Gauss Seidel Matrix1 is coeff matrix generated by previous functions

Really appreciate any help. TY