[Python-ideas] PEP 3150 (statement local namespaces) updated based on April discussion

Greg Ewing greg.ewing at canterbury.ac.nz
Tue Jun 14 02:47:10 CEST 2011

Terry Reedy wrote:

> Part of my point is that the above is not *code* (and hence not an 
> argument for formatting code that way).

A couple of things about that:

1) Mathematicians often write things informally that, in a program,
would need to be spelled out formally in code. They get away with
it because they're writing for humans, not computers.

2) Very often they *do* write out the subsequently-defined terms
formally. I came across an example just the other day. From
"Elementary Numerical Analysis, an Algorithmic Approach" by
Samuel D. Conte and Carl de Boor, 3rd edition, page 364:

    Runge-Kutta method of order 4:

       y[n+1] = y[n] + (1/6) * (k1 + 2*k2 + 2*k3 + k4)


       k1 = h*f(x[n], y[n])
       k2 = h*f(x[n + h/2], y[n] + k1 / 2)
       k3 = h*f(x[n + h/2], y[n] + k2 / 2)
       k4 = h*f(x[n], y[n] + k3)


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