How do I change the display of my answers if condition is not met?

Question

Aaron 2012-6-28

0
链接

此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/42303-how-do-i-change-the-display-of-my-answers-if-condition-is-not-met

Here is what I have so far:

*format compact                          
a=input('Enter value for side a: ');    
if a <= 0                               
  disp('Not a valid input.');break;   
end
b=input('Enter value for side b: ');    
if b <= 0                               
  disp('Not a valid input.');break;   
end
c=input('Enter value for side c: ');    
if c <= 0                               
  disp('Not a valid input.');break;   
if a > b+c                              
  fprintf('\n');                      
  disp('Error: Side "a" must be less than the sum of sides b & c.') % 
elseif b > a+c                          
  fprintf('\n');                      
  disp('Error: Side "b" must be less than the sum of sides a & c.')
elseif c > a+b                          
  fprintf('\n');                      
  disp('Error: Side "c" must be less than the sum of sides a & b.')
end
fprintf('\n');                          
A=acosd((b^2+c^2-a^2)/(2*b*c)); 
B=acosd((a^2+c^2-b^2)/(2*a*c)); 
C=acosd((a^2+b^2-c^2)/(2*a*b)); 
disp('Results:')
fprintf('Angle A = %G',A);disp(' degrees') 
fprintf('Angle B = %G',B);disp(' degrees') 
fprintf('Angle C = %G',C);disp(' degrees') *

When the conditions that provide the "Error" message are not met, I still get something like:

Angle A = 180 degrees Angle B = 0 degrees Angle C = 0 degrees

But I would like to have my program display something when there could be no viable answers, like:

Angle A = NaN degrees Angle B = NaN degrees Angle C = NaN degrees

or

Any message I choose.

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Answer 1

Sean de Wolski 2012-6-28

0
链接

此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/42303-how-do-i-change-the-display-of-my-answers-if-condition-is-not-met#answer_52071

在 MATLAB Online 中打开

Why don't you use error() instead of disp('...') to actually abort the program when the error is encountered.

Or, to keep what you have and make the if-decision tree work:

if
elseif
elseif
else
   %we haven't errored, woohoo!
    fprintf('\n');                          
    A=acosd((b^2+c^2-a^2)/(2*b*c)); 
    B=acosd((a^2+c^2-b^2)/(2*a*c)); 
    C=acosd((a^2+b^2-c^2)/(2*a*b)); 
    disp('Results:')
    fprintf('Angle A = %G',A);disp(' degrees') 
    fprintf('Angle B = %G',B);disp(' degrees') 
    fprintf('Angle C = %G',C);disp(' degrees') *
end