# Revision history [back]

Expanding on my remark:

Functions defined in the way above don't say they have just one variable for input (their expression could, in theory, have some constants like c or a that shouldn't be substituted, only t), so we have to do this:

sage: t = var('t')
sage: uR = function('uR', t).function(t)
sage: iL = function('iL', t).function(t)
sage: uC = function('uC', t).function(t)
sage: SE = uR(t) == 3*iL(0) + uC(0)/2 -4
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