I have a problem with fprintf function, MATLAB

Question

hgrlk 2019-3-27

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https://ww2.mathworks.cn/matlabcentral/answers/452886-i-have-a-problem-with-fprintf-function-matlab

评论： hgrlk 2019-3-27

采纳的回答： Stephen23

在 MATLAB Online 中打开

Hello,

I have a question about my matlab code. I wrote my code, but when I run my code, output look is wrong.

I want a output that gives me my results in tabulated form in which the first column shows the number of terms ( in my code m represents the term) , the second column lists the approximation value ( in my code sum represent the app. value), third column shows the true value( in my code truevalue represents that), fourth column show the Et true percent relative error (in my code Et represent that) and finally fifth column represents the Ea error (in my code Ea represents that).

But when I run my code, the output is very wrong.

Thanks for the help.

clc
clear all
close all
x = -2.5;
truevalue = log(exp(1)+x);  %my true value is -1.5220
Ea= 100;
Es = 0; %First error
m=1;
sum=1;%sum is represents the formula of ln(e+x) given in the question.
fprintf('\tn\t  app.\t  true value\t    Et\t    Ea\n')
while abs(Ea) >= Es
    Es = (0.5*10^-2)/100;
    sump = sum;
    sum = sum + (((-1)^(m-1))/m)*((x/m)^m); %sum is my approximate value
    Et = abs(( ( truevalue - sum ) / truevalue )*100);
    Ea = (( sum - sump ) / sum ) * 100;
    fprintf('%10.4f\t\t %10.4f\t %10.4f\t\t %10.4f\n',m,sum,truevalue,Et,abs(Ea))
    m = m+1;
    
end

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Answer 1

Stephen23 2019-3-27

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此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/452886-i-have-a-problem-with-fprintf-function-matlab#answer_367759

编辑：Stephen23 2019-3-27

在 MATLAB Online 中打开

You only defined four number conversions within the format string, but you have provided five inputs to fprintf. Start by writing the format string with the correct number of conversions.

To align the columns simply specify the fieldwidths (and avoid unpredictable tabs):

% Print header:
fprintf('%10s %10s %10s %10s %10s\n','m','app','truevalue','Et','Ea');
for...
    ....
    % Print data:
    fprintf('%10.4f %10.4f %10.4f %10.4f %10.4f\n',m,sum,truevalue,Et,abs(Ea))
end

Which prints this:

         m        app  truevalue         Et         Ea
0000    -1.5000    -1.5220     1.4434   166.6667
0000    -2.2812    -1.5220    49.8881    34.2466
0000    -2.4742    -1.5220    62.5626     7.7967
0000    -2.5123    -1.5220    65.0690     1.5184
0000    -2.5185    -1.5220    65.4797     0.2482
0000    -2.5194    -1.5220    65.5370     0.0346
0000    -2.5195    -1.5220    65.5439     0.0042
0000    -2.5195    -1.5220    65.5447     0.0005
0000    -2.5195    -1.5220    65.5448     0.0000