Undefined Variable

General Usage Performance
1

function Plot_Poisson_Equation(n)
A = zeros(n-1,n-1)

       for i in 1:n-2
  
           A[i,i+1] = -1
           A[i,i]   = 2
           A[i+1,i] = -1
       end
   end

Hello Im still gettin Erro A, and u not defined, can someone help me please?

2

Looks good to me:

julia> function Plot_Poisson_Equation(n)
          A = zeros(n-1,n-1)
              for i in 1:n-2

                  A[i,i+1] = -1
                  A[i,i]   = 2
                  A[i+1,i] = -1
              end
          A
          end
Plot_Poisson_Equation (generic function with 1 method)

julia> Plot_Poisson_Equation(10)
9×9 Array{Float64,2}:
  2.0  -1.0   0.0   0.0   0.0   0.0   0.0   0.0   0.0
 -1.0   2.0  -1.0   0.0   0.0   0.0   0.0   0.0   0.0
  0.0  -1.0   2.0  -1.0   0.0   0.0   0.0   0.0   0.0
  0.0   0.0  -1.0   2.0  -1.0   0.0   0.0   0.0   0.0
  0.0   0.0   0.0  -1.0   2.0  -1.0   0.0   0.0   0.0
  0.0   0.0   0.0   0.0  -1.0   2.0  -1.0   0.0   0.0
  0.0   0.0   0.0   0.0   0.0  -1.0   2.0  -1.0   0.0
  0.0   0.0   0.0   0.0   0.0   0.0  -1.0   2.0  -1.0
  0.0   0.0   0.0   0.0   0.0   0.0   0.0  -1.0   0.0
1 Like