MATLAB Answers

Implicit function inside a loop.

16 views (last 30 days)
Anshuman S
Anshuman S on 21 Jan 2018
Commented: Anshuman S on 21 Jan 2018
I want to plot a curve between err and b for different values of b.
  • I have kept the values of i to be a constant for the inner iteration, and I want to sum up the error ( square )
  • In 'o' and 'p'for different values of 'i' and finally I want to plot err vs b. such that i get a minimum to this curve at a certain 'b'.
sum =0;
err =0;
for b= 0:1:40
for i= 0:1:50
f1 = @(o,i) (sind(b+i) + sind(b-o)) -( 1.180/0.04 + sqrt.((1.140/0.04 - 2*sind(b)).^2 - (cosd(b-o)- cosd(b+i)).^2));
f2 = @(p,i) cotd(p-3.34) - cotd(i-1.07) - (1.180/(1.540 - 0.300));
sum = sum + (o - p).^2;
end
err = sqrt(sum/50);
plot (b,err);
hold on
end

  1 Comment

Anshuman S
Anshuman S on 21 Jan 2018
I want to use these equations to get the values of 'o' and 'p' which are to be solved for same value of 'i'. Now that i have 'o' and 'p' values in terms of 'b' . I want to sum this for all the 'i's in the inner loop . further when i come out of the loop I want to plot a point (b, err) , the value of b comes from the outer loop. hence i'll get a set of 40 points for err vs b and i'll draw a curve to fit these data.
Thanks

Sign in to comment.

Answers (1)

Walter Roberson
Walter Roberson on 21 Jan 2018
total = 0;
err = 0;
bvals = 0:1:40;
for b = bvals
subtotal = 0;
for i= 0:1:50
f1 = @(o,i) (sind(b+i) + sind(b-o)) -( 1.180/0.04 + sqrt.((1.140/0.04 - 2*sind(b)).^2 - (cosd(b-o)- cosd(b+i)).^2));
f2 = @(p,i) cotd(p-3.34) - cotd(i-1.07) - (1.180/(1.540 - 0.300));
subtotal = subtotal + (o - p).^2;
end
err = sqrt(subtotal/50);
plot(bvals,err);
hold on
total = total + subtotal;
end
But why do you define f1 and f2 when you do not use them? And you have not defined o or p but you try to add their squared difference to the total?

  3 Comments

Image Analyst
Image Analyst on 21 Jan 2018
And even if you did use them, why do you want them to be defined inside a loop instead of at the top of your program?
And don't use sum as the name of your variable since it's a built in function.
Anshuman S
Anshuman S on 21 Jan 2018
The inner loop varies for 'i' and I want to work (subtotal = subtotal + (o - p).^2) with those values of 'o' and 'p' which come out from the equation f1 and f2 respectively.
Anshuman S
Anshuman S on 21 Jan 2018
I want to use these equations to get the values of 'o' and 'p' which are to be solved for same value of 'i'. Now that i have 'o' and 'p' values in terms of 'b' . I want to sum this for all the 'i's in the inner loop . further when i come out of the loop I want to plot a point (b, err) , the value of b comes from the outer loop. hence i'll get a set of 40 points for err vs b and i'll draw a curve to fit these data.
Thanks.

Sign in to comment.

Community Treasure Hunt

Find the treasures in MATLAB Central and discover how the community can help you!

Start Hunting!