Fixing Loop Troubles in Maple for Gauss Seidel Iteration

[elarson89]

I am trying to write a Gauss Seidel iteration for maple, but my troubles are because of a nested for loop.

What i want to do is like this,
function := proc(...)
for ... do
for ... do
(computations)
end do;
(if something > something, then return solution);
end do;

return solution;
end proc;

the statement if something > something is giving me troubles. Even if i don't include a return statement i get the error. It seems like I'm not allowed to put anything in between the end do's.
What am i doing wrong and how can i fix this?

My exact code is this:

with (linalg);

gauss_seidel := proc (A, B, x_0, eps, N) local i, j, k, m, n, x, sol;

n := coldim(A);
for i from 1 to n do
x[i,1] := x_0
od;

for m from 1 to N do
for j from 1 to n do

x[j,m+1] := 1/A[j,j] * ( B[j] - sum(A[j,k]*x[k,m+1] , k=1..(j-1)) - sum( A[j,k]*x[k,m], k=(j+1)..n))

end do;
if abs( max( [seq(x[i,m+1], i=1..n)] - [seq(x[i,m], i=1..n)])) < eps then return (<seq(x[i,m+1], i=1..n)>);

end do;

return <seq(x[i,N+1], i=1..n)>;
end proc;

 

[NateD]

The error occurs when I try to add the "if" statement. How can I fix my code so that I can make the comparison?

 

[oswaler]

I can understand your frustration with the nested for loop and the if statement causing errors in your Gauss Seidel iteration for Maple. It is important to carefully check the syntax and logic of your code to identify the root cause of the error.

One possible issue could be the use of the return statement within the nested for loop. In Maple, the return statement immediately exits the current procedure and returns a value. This means that when the condition in the if statement is met, the loop will terminate and the procedure will return a solution. However, this may not be what you intend for the loop to do. Instead, you may want to use a break statement to exit the loop and continue with the next iteration.

Another potential issue could be the use of the seq() function in the if statement. This function creates a sequence of values, but it may not be appropriate to use in this context. Instead, you may want to use the max() function to compare the maximum values of the two sequences.

To fix these loop troubles, you may need to revise your code and carefully consider the purpose of each statement and function. It may also be helpful to consult the Maple documentation or seek assistance from other Maple users to troubleshoot and optimize your code.