implict term bug fix in Octave addScalarBC

[bewagner1]

What type of PR is this? (check all applicable)

• Refactor
• Feature
• Bug Fix
• Optimization
• Example
• Documentation

Description

Both addScalarBC2D and addScalarBC3D silently fail when there are implicit (linear) terms in the operator they are adding boundary conditions to.
The line [rows1,cols1,s1] = find(A(rowsbc1,:)) causes rows1 to be [1; 2; 3; 4; ...; numel(rowsbc1)] when there are non-zero terms present in A(rowsbc1,:). This results in the left, right, and top boundary conditions being incorrectly applied as the line A = A - sparse(rows1, cols1, s1, size(A,1), size(A,2)) does not correctly zero out the boundary rows.

This is fixed by replacing the problematic lines mentioned above with A(rows1,:) = sparse(numel(rows1),size(A,2));

addScalarBC1D does not have this problem.

Related Issues & Documents

• I have created an Issue that is paired with this PR
• Closes addScalarBC2D fails with implicit terms #475

QA Instructions, Screenshots, Recordings

Run the following code snippet with the current implementation and compare with the results from the fixed version presented below:

k = 2;
m = 10;
n = 11;
o = 12;
dx = 1 / m;
dy = 1 / n;
dz = 1 / 0;

dc = [1;1];
nc = [0;0];
v = [0;0];

D =  div(k, m, dx, dc, nc);
G = grad(k, m, dx, dc, nc);

numC = m + 2;
L = D * G - spdiags(5 * ones(numC, 1), 0, numC, numC);

figure; spy(L); title("1D Before")
[L0,~] = addScalarBC1D(L,zeros(numC,1),k,m,dx,dc,nc,v);
figure; spy(L0); title("1D After")

dc = [1;1;1;1];
nc = [0;0;0;0];
v = {zeros(n,1);zeros(n,1);zeros(m+2,1);zeros(m+2,1)};

D =  div2D(k,m,dx,n,dy,dc,nc);
G = grad2D(k,m,dx,n,dy,dc,nc);

numC = (m + 2) * (n + 2);
L = D * G - spdiags(5 * ones(numC,1), 0, numC, numC);

figure; spy(L); title("2D Before")
[L0,~] = addScalarBC2D(L,zeros(numC,1),k,m,dx,n,dy,dc,nc,v);
figure; spy(L0); title("2D After")

dc = [1;1;1;1;1;1];
nc = [0;0;0;0;0;0];
v = {zeros(o*n,1);zeros(o*n,1);zeros(o*(m+2),1);zeros(o*(m+2),1);zeros((n+2)*(m+2),1);zeros((n+2)*(m+2),1)};

D =  div3D(k,m,dx,n,dy,o,dz,dc,nc);
G = grad3D(k,m,dx,n,dy,o,dz,dc,nc);

numC = (m + 2) * (n + 2) * (o + 2);
L = D * G - spdiags(5 * ones(numC,1), 0, numC, numC);

figure; spy(L); title("3D Before")
[L0,~] = addScalarBC3D(L,zeros(numC,1),k,m,dx,n,dy,o,dz,dc,nc,v);
figure; spy(L0); title("3D After")

Keep-open request

• I am requesting maintainer review for keep-open.

Reason:

Added/updated tests?

• Yes
• No, and this is why: Don't know how to write Octave test cases
• I need help with writing tests

Read Contributing Guide and Code of Conduct

• 📖 I have read the MOLE Contributing Guide: https://github.com/csrc-sdsu/mole/blob/main/CONTRIBUTING.md
• 📖 I have read the MOLE Code of Conduct: https://github.com/csrc-sdsu/mole/blob/main/CODE_OF_CONDUCT.md

[optional] Are there any post deployment tasks we need to perform?

No

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