CAS Integration constant (c_1) seems to increase to c_2, c_3,... arbitrarily

pirsquared shared this problem 5 years ago

In Progress

Hi,

I am creating a worksheet for students to demonstrate integration, using the CAS (behind the scenes) to do some fairly primitive substitutions and then display them as a step-by-step guide:

http://ggbtu.be/mC9PxnBPx

Initially I had a Substitute[$1,c_1,0] to eliminate the constant of integration from the display and from further substitutions - this was fine until I saved the worksheet and the next time I loaded it, it had changed to c_2. Not a huge problem, I just used Substitute[$1,{c_1=0,c_2=0}] etc. but on each save it then increases the constants subscript. I tried to be clever and anticipate c_10 and c_11 when it got that high, and it just gave me c_12 as shown above!

I am guessing that maybe it's because c_10 and c_11 are "used" in the Substitute command, it uses the next available - c_12 - for the constant of integration, meaning that it seems to process $2 before $1. Can anyone offer a way I can reliably "cleanse" that c_x that will survive a reload of the worksheet?

Thank you.