Maple Loop Troubles: Fixing Newton's Method Procedure

[cdotter]

Homework Statement

I'm trying to make a Newton's method procedure in Maple, but I can't figure out what's wrong.

Homework Equations

Newton := proc (func, iterations, guess)
f := unapply(func, x);
fprimej := diff(f(x), x);
fprime := unapply(fprimej, x);
for i from 1 to iterations do:
     value := evalf(guess-f(guess)/fprime(guess));
     printf("Iteration %d: %a\n", i, value);
     guess := value;
end do;
end proc;

The Attempt at a Solution

Something is going wrong when I assign "guess" to "value" because it works fine if I hard code a "guess" value in. What's the correct (and error free) way of assigning "guess" to "value?" Thank you.

 

[Päällikkö]

I've got very little experience in coding Maple, so this is probably a bit of a hack. Apparently you can't properly define new variables in the function input, i.e. the "guess" you give the function seems not to be a proper variable. I changed it to guesso and added guess := guesso; as the first line. It worked.

Newton := proc (func, iterations, guesso)
guess := guesso;
f := unapply(func, x);
fprimej := diff(f(x), x);
fprime := unapply(fprimej, x);
for i from 1 to iterations do:
     value := evalf(guess-f(guess)/fprime(guess));
     printf("Iteration %d: %a\n", i, value);
     guess := value;
end do;
end proc;

 

[cdotter]

I've got very little experience in coding Maple, so this is probably a bit of a hack. Apparently you can't properly define new variables in the function input, i.e. the "guess" you give the function seems not to be a proper variable. I changed it to guesso and added guess := guesso; as the first line. It worked.

Newton := proc (func, iterations, guesso)
guess := guesso;
f := unapply(func, x);
fprimej := diff(f(x), x);
fprime := unapply(fprimej, x);
for i from 1 to iterations do:
     value := evalf(guess-f(guess)/fprime(guess));
     printf("Iteration %d: %a\n", i, value);
     guess := value;
end do;
end proc;

Thank you, that works perfectly.