why is my error plot not showing?

x = linspace(-10,10,100);
h = logspace(-1,-16,100);
error = (300);
figure(1);
hold on;
for i = 1:100
    error(i) = abs(1-(exp(h(i)-exp(h(i))))/(h(i)));
    plot(x,error(i));
end
disp([error']);

Answer 1

[John BG]

Hi Luis Garcia

this is John BG <mailto:[e-mail] [e-mail]>

there's no need for a for loop

x = linspace(-10,10,100);
h = logspace(-1,-16,100);
err=abs(ones(1,numel(h))-(exp(h-exp(h)))./h)
plot(x,err);grid on

.

and since you wish a display of the error, perhaps you would like to consider a table:

.

T1=table(x',err')

T1 =
  100×2 table
           Var1                   Var2        
    __________________    ____________________
                   -10        2.65982076505758
      -9.7979797979798        4.20132574336608
      -9.5959595959596        6.38225249098713
     -9.39393939393939        9.47080574029657

..

        7.57575757575757        55914403982699.7
        7.77777777777778          79257222980929
        7.97979797979798         112345065800796
        8.18181818181818         159246228104940
        8.38383838383838         225727413882301
        8.58585858585858         319962777042449
        8.78787878787879         453538969555982
        8.98989898989899         642879771226050
        9.19191919191919         911265465581224
        9.39393939393939    1.29169525302885e+15
         9.5959595959596     1.8309446475436e+15
         9.7979797979798    2.59531673164217e+15
                      10    3.67879441171442e+15

.

Luis

If you find this answer useful would you please be so kind to consider marking my answer as Accepted Answer?

To any other reader, if you find this answer useful please consider clicking on the thumbs-up vote link

thanks in advance

John BG

<mailto:[e-mail] [e-mail]>

Modified Answer: Applied Jan Simon's advice not to use any variable named 'error', thanks

Answer 2

[Jan]

Do not use "error" as a name of a variable, because this shadows an important built-in function with the same name. Afterwards trying to call error() can have unexpected results.

What is the purpose of

error = (300);

? Do you mean:

error = zeros(1, 100);

as a pre-allocation?

x = linspace(-10, 10, 100);
h = logspace(-1, -16, 100);
err = zeros(1, 100);
figure(1);
hold on;
for i = 1:100
    err(i) = abs(1 - (exp(h(i) - exp(h(i)))) / (h(i)));
    plot(x(i), err(i), 'o');
    %     ^^^          ^^^  modified
end

If you plot only single points, they are not visible. Use a marker like the 'o' to make them visible.

The other answers explained how to plot outside the loop. I wanted to add an explanation of why you do not see the plot with your method.

Answer 3

[Star Strider]

The plot call needs to go after the loop:

figure(1);
hold on;
for i = 1:100
    error(i) = abs(1-(exp(h(i)-exp(h(i))))/(h(i)));
end
plot(x,error)
hold off