How to solve this without goto statement?

Question

Amit Kumar 2014-5-16

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评论： Amit Kumar 2014-5-16

Hi all, I think it is bad that matlab doesn't have a goto statement (many people will strongly disagree, but excuse me for the same). I am not a great programmer and I do not know what alternative should be used in the following script:

m1=2140.67; 
m2=0.2*m1; 
F=440; 
k1=0.7*1e6;
w1=sqrt(k1/m1);
c1=10; c2=0; c3=0;
for(k2=1e3:1:1e5) 
   for (w=18:1e-4:18.1) 
       x1 = 1/(((-m1*w^2+k1+k2)*(-m2*w^2+k2) - k2^2))*k2*F*1;
       % if(abs(x1)>0.0025)
       % { goto abc}
       if(abs(x1)<c1 && abs(x1)<(0.0025))
             c1=x1;
             c3=k2;
         else
         end
     end
     %abc:
     %continue;
  end
   fprintf('val : x1 = %4.6f m  and k2 = %4.6f N/m \n',c1,c3);

There are 2 for loops in this script. I wish that for any value of w, if (abs(x1)>0.0025), the next iteration should begin in outer loop (not the loop of w, so 'continue' is not useful). So what should I do to get next iteration of outer loop i.e. next iteration of k? Had matlab been using goto, I could have employed what is given in % (comments).

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Answer 1

Image Analyst 2014-5-16

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编辑：Image Analyst 2014-5-16

在 MATLAB Online 中打开

I don't see a loop over k, just k2. But when that condition happens, put a break in the inner loop

if (abs(x1)>0.0025)
  break;
end

and then outside the inner loop but inside the outer k2 loop, put this:

if (abs(x1)>0.0025)
  continue;
end

x1 will still have the same value so that should work.

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Image Analyst 2014-5-16

在 MATLAB Online 中打开

Haven't heard from you so perhaps you need it spelled out exactly. See below:

clc;
workspace;
m1=2140.67;
m2=0.2*m1;
F=440;
k1=0.7*1e6;
w1=sqrt(k1/m1);
c1=10; 
c2=0;
c3=0;
tic;
for k2 = 1e3 : 1e5
  for w = 18 : 1e-4 : 18.1
    x1 = 1/(((-m1*w^2+k1+k2)*(-m2*w^2+k2) - k2^2))*k2*F*1;
    if abs(x1) > 0.0025
      break;
    end
    if (abs(x1) < c1 && abs(x1) < (0.0025))
      c1=x1;
      c3=k2;
    end
  end
  if abs(x1) > 0.0025
    continue;
  end
end
toc
fprintf('val : x1 = %4.6f m  and k2 = %4.6f N/m \n',c1,c3);

I cleaned up a few other things too.

Amit Kumar 2014-5-16

Thanks a lot!

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Answer 2

the cyclist 2014-5-16

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I am not 100% I understand the logic you are trying to implement, but I think you want the break command.

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Answer 3

Brian B 2014-5-16

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在 MATLAB Online 中打开

for(k2=1e3:1:1e5)
    for (w=18:1e-4:18.1)
        x1 = 1/(((-m1*w^2+k1+k2)*(-m2*w^2+k2) - k2^2))*k2*F*1;
        if(abs(x1)>0.0025)
            break;
        elseif(abs(x1)<c1 && abs(x1)<(0.0025))
            c1=x1;
            c3=k2;
        end
    end
end