It appears to do repeated subtractions of the entire denominator array. When the difference is less than the denominator it stops.
I found some errors in your VI while trying to see if I could speed it up. I now have it so thoroughly broken that it never stops! The tests in the while loop may be wrong. The algorithm (D3) says to repeat the test if r* < b, but you have it stopping the loop. The q*v[n-2] > br*+u[j+n-2] may not be quite right also. However, changing those still did not get it working.
Lynn
