******************* This email originates from outside Imperial. Do not click on links and attachments unless you recognise the sender. If you trust the sender, add them to your safe senders list https://spam.ic.ac.uk/SpamConsole/Senders.aspx to disable email stamping for this address. ******************* Hello, I am calling PhysDeriv from an Expansion Class Object. Why is this not linear? In the sense that if I call PhysDeriv for any linear combination of vectors it should be the same as computing the linear combination of the PhysDeriv of the vectors. Martin Hess -- -- Martin Hess, Ph.D., Post-doctoral research fellow SISSA mathLab, International School for Advanced Studies Office A-434 (4th floor), via Bonomea 265, I-34136 Trieste, Italy phone: +39 040 3787 491 email: mhess@sissa.it