"Ben Blomberg" <bblomberg1 at niu.edu> writes:
> I was wondering if there is some function in Maxima that acts like a
> do loop in Mathematica? Something that would like do[eval, {i, imin,
> imax},{j, jmin, jmax}]. In other words it evaluates an expression
> looking over different values of j for each i.
> Or would something like this need to be done in a different way?
If I understand you, you want a nested loop (so eval gets evaluated
(jmax-jmin+1)*(imax-imin+1) times). In Maxima, you just use two loops:
(%i1) for i : 1 thru 3 do
for j : 1 thru 3 do
print ([i,j]);
[1, 1]
[1, 2]
[1, 3]
[2, 1]
[2, 2]
[2, 3]
[3, 1]
[3, 2]
[3, 3]
(%o1) done
Look up "do" in the manual for more examples: you can iterate over lists
as well, rather than having to do it with "for i:1 thru length(list)
..."
Notice that this is a bit like for(...) in C without any curly braces.
Only the following statement gets iterated. If you want several
statements, you can enclose them in brackets like this:
(%i2) for i : 1 thru 2 do
for j : 1 thru 2 do
(print ([i,j]),
print ([j,i]))$
[1, 1]
[1, 1]
[1, 2]
[2, 1]
[2, 1]
[1, 2]
[2, 2]
[2, 2]
That said, when writing programs, you often want to bind variables in
the loop body, so you'll often see block used:
(%i3) for i : 1 thru 2 do
for j : 1 thru 2 do
block ([pair: [i,j]],
print (pair),
print (reverse (pair)))$
[1, 1]
[1, 1]
[1, 2]
[2, 1]
[2, 1]
[1, 2]
[2, 2]
[2, 2]
(Yes, this is a very silly example)
Rupert
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