1. The problem statement, all variables and given/known data The problem given is...Calculate mI+1 and lI+1 at point xI+1 using equation (5), the values of the slopes at points xI+1 and xI from equation (4), and the values of mI and lI from the previous step. Here is a screenshot of my solar model 2. Relevant equations 3. The attempt at a solution I need help with columns I and J. For column I, I have the equation entered as =SUMPRODUCT(I2+1/2*(G3+G2)*B3-B2) For J I have =SUMPRODUCT(J2+1/2*(H3+H2)*B3-B2) and for some reason I'm getting negative values when as it goes down it should be getting closer to 1 Thanks in advance!