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

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DIJESH
DIJESH 2014-5-27
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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采纳的回答

Jos (10584)
Jos (10584) 2014-5-27
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!

更多回答（1 个）

rifat
rifat 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
sum=0;
for jj=1:numel(a)
string='f(jj)*cos(jj)';
sum=sum+eval(string);
end

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