Hi, I've got this two functions:
psi=function('psi',t)
psi_d=function('psi_d',t)
psi=(sin(delta(t))*v(t))/(l*cos(delta(t)))
psi_d=diff(psi)
but it says No differentiation variable specified how can I derivate psi? Please someone help me it's driving me crazy since yesterday!
Thank you very much
You have to specify the derivation variable t:
sage: diff(psi,t)
v(t)*D[0](delta)(t)/l + sin(delta(t))^2*v(t)*D[0](delta)(t)/(l*cos(delta(t))^2) + sin(delta(t))*D[0](v)(t)/(l*cos(delta(t)))
Asked: 2015-01-12 12:52:24 +0100
Seen: 1,074 times
Last updated: Jan 12 '15
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By the way, in general the first thing you should do when you encounter an error like that is to make sure you didn't accidentally make a mistake in the syntax. This help can be gotten by typing
diff?and it should tell you then that you need the variable of differentiation, as pointed out below.