u1 =
How exactly does this reordering "change the meaning of the equation"? The derivative of 
with respect to x is 
. In this case, x is c and k is 
. So the derivative of 
is 
or 
. Multiply that by the constant 
and the derivative is 
or 
exactly as MATLAB showed.
with respect to x is . In this case, x is c and k is . So the derivative of is or . Multiply that by the constant and the derivative is or exactly as MATLAB showed.Sure, the way MATLAB displays u is not identical to the way you entered it, but it represents the same value.
