How do i add all the values which i get using eval function?

Question

DIJESH 2014-5-27

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此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/131282-how-do-i-add-all-the-values-which-i-get-using-eval-function

评论： DIJESH 2014-5-27

prompt = {'Enter the forces(kN): '};
title = 'Environmental forces';
answer = inputdlg(prompt,title);
f = str2num(answer{:});
for ii=1:numel(f)
    eval(sprintf('f%d = %f\n',ii,f(ii)))
end
prompt1 = {'Enter the respective angles: '};
title1 = 'Angle w.r.t x-axis';
answer1 = inputdlg(prompt1, title1);
a = str2num(answer1{:});
for jj=1:numel(a)
    eval(sprintf('a%d = %f\n',jj,a(jj)))
end
for jj=1:numel(a)
    string='f(jj)*cos(jj)';
    eval(string)
end
in this code i am getting several values for string. I have to add all those values. can anyone help?

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Answer 1

Jos (10584) 2014-5-27

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https://ww2.mathworks.cn/matlabcentral/answers/131282-how-do-i-add-all-the-values-which-i-get-using-eval-function#answer_138408

在 MATLAB Online 中打开

Avoid EVAL !!!

You do not want to store a series of related values in separate variables f1 = .. f2 = .. but rather in a single variable with multiple elements f(1) = .. f(2) = ..

Your codes is almost there. Just remove the evals ...

prompt = {'Enter the forces(kN): '};
title = 'Environmental forces';
answer = inputdlg(prompt,title);
f = str2num(answer{:});
prompt1 = {'Enter the respective angles: '};
title1 = 'Angle w.r.t x-axis';
answer1 = inputdlg(prompt1, title1);
a = str2num(answer1{:});
if numel(f) ~= numel(a)
   error('The vectors should have the same number of elements') ;
else
   sum=0 ;
   for jj=1:numel(a)
      sum = sum + f(jj)*cos(a(jj)) ;
   end
   % or use the power of matlab:
   % sum = sum(f.*cos(a)) 
end

Lesson to be learned: avoid eval!

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DIJESH 2014-5-27

thank you for the help!!! :)

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Answer 2

rifat 2014-5-27

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此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/131282-how-do-i-add-all-the-values-which-i-get-using-eval-function#answer_138390

在 MATLAB Online 中打开

prompt = {'Enter the forces(kN): '};
title = 'Environmental forces';
answer = inputdlg(prompt,title);
f = str2num(answer{:});
for ii=1:numel(f)
    eval(sprintf('f%d = %f\n',ii,f(ii)))
end
prompt1 = {'Enter the respective angles: '};
title1 = 'Angle w.r.t x-axis';
answer1 = inputdlg(prompt1, title1);
a = str2num(answer1{:});
for jj=1:numel(a)
    eval(sprintf('a%d = %f\n',jj,a(jj)))
end
sum=0;
for jj=1:numel(a)
    string='f(jj)*cos(jj)';
    sum=sum+eval(string);
end