MATLAB: Problem with ‘if-elseif-else’

elseelseifif

In order to show the appropriate root for the problem I created this code :

   if riza > 1 | riza<0  
  fprintf('so the correct root is',root1)
  elseif riza1>1 |riza1<0 
  fprintf ('so the correct root',root)
  end

Even though it appears the message 'so the correct root is' ,it won't appear the root1 or root.How can this be fixed ?

Best Answer

% code
 if riza > 1 | riza<0  
fprintf('so the correct root is %f\n',root1)
elseif riza1>1 |riza1<0 
fprintf ('so the correct root %f \n',root)
end

Related Solutions

MATLAB: Trying with bisection method to create a function that finds the root of an equation, approximated error, and numbers of iteration

A first problem in your code is that the returned variable "root" does not always take a value. A second one is the "i= i+1;". i is the index of the loop so there is no need to increase it. Furthermore it would be good to test also if one of the initial limits is the root. An example of what you want do to is the following.

function root= bisection(fun, lb, ub,iter_max, Emax)
flb=fun(lb); % find the f(lb) value
fub=fun(ub); % find the f(ub) value
i=0; % the initial iteration
%Check if you have already found the solution
if flb==0
   root=lb;
   fprintf('The root is: %5.3f \n', root)
   return
end
if fub==0
   root=ub;
   fprintf('The root is: %5.3f \n', root)
   return
end
%now to test if there is a root within the uppper and lower limits
if flb*fub>0
   disp('termination type 1: there is no root within bracket')
   root=NaN;
   return
end
%solution guess
root= (lb+ub)/2;
for i=1:iter_max
    rootPrevious=root;
    fxr=fun(root);
    if i >= iter_max
       disp('termination type 0: algorithm terminated due to maximum interations')
       break
    elseif fxr==0  % test if this is the case where root is directly the root  
       disp('this is the root')
       break
    end
    % if none of above is met, then process the commands below
    if fxr*flb>0
       lb=root;
    else
       ub=root;
    end
    root= (lb+ub)/2;
    error=abs((root-rootPrevious)/root);
    if error<Emax
        break
    end
end
fprintf('The iterations taken is: %d \n', i)
fprintf('The root is: %5.3f \n', root)

MATLAB: Switch case or if-elseif-else

In general, using a switch case gives better readability to the code. But, in your case, there isn't much difference as there are only three cases.

Coming to the more logical(less error), as both implement the same thing, there is no one better than the other in terms of logic.

Hope this helps.

Best Answer

Related Solutions

MATLAB: Trying with bisection method to create a function that finds the root of an equation, approximated error, and numbers of iteration

MATLAB: Switch case or if-elseif-else

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