Talk:Nonlinear finite elements/Nonlinear axially loaded bar

I think the second last equation is wrong, or at least I don't see how $$ \left(\sum_j u_j\cfrac{dN_j}{dx}\right)^2 = \sum_j u_j \left(\cfrac{dN_j}{dx}\right)^2 $$


 * I had the same thought after reading it. There should remain terms with $$ u_j $$ squared, which makes it not possible anymore to write the DE as a matrix problem. This makes sense to me, since it is a nonlinear DE in the first place. I think it is wrong and should be corrected/removed. --141.135.57.121 (discuss) 23:33, 10 September 2014 (UTC)
 * Thank you to all of you who pointed this out. The expression has been corrected. 203.160.120.29 (discuss) 20:11, 31 August 2016 (UTC)