I continue to stumble over the "." in structures other than in filenames. For example,
Dr(t) = sol[0].rhs
where D is the first derivative of r and "sol" has been defined as the Sagemath function "solve" in lines before this one.
This is the way to apply a method to an object.
Very often, instead of f(x), the notation in Python, and therefore in SageMath,
will be x.f().
Follow a Python tutorial or a Sage tutorial to learn more.
In the example you mention, sol[0] is an equation,
and to extract its right-hand side, you apply the method "rhs" to it,
by doing sol[0].rhs().
This is very efficient, especially when you need to apply several operations in a row.
For example, starting from a graph, say you want to compute its adjacency matrix, then get the characteristic polynomial of this matrix, then factor this polynomial.
You can do g.adjacency_matrix().charpoly().factor(), which maybe better
shows the sequence of operations, and avoids nested parenthesis, if you compare
to writing factor(charpoly(adjacency_matrix(g))).
THANK YOU, THANK YOU!! I'm just starting out using SageMath. Even at this early stage it's been a real time-saver. There are some structures, however, that are confusing and trying to find answers can be difficult. This one is a case in point. I scrolled through the Python codes but I can see I need to invest time in the tutorial(s). Thanks again for pointing towards the resources I'll need.
Asked: 2018-04-09 04:36:59 +0100
Seen: 273 times
Last updated: Apr 12 '18
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