Percent Error

Below is some coding I have calculating percent error of Euler's method however there has to be a more efficient way to input the matrices, I have found the first two step size errors by manually inputing the values but before I do the third (extremely long), there has to be a faster way. Any suggestions?

%%Analytical
simplify(dsolve('Dy=-x/y','y(0)=5','x'))
%%Numerical
f=@(x) (-x^2+25)^(1/2)
dydx=@(x,y) -(x/y);
[x1,y1]=eulode(dydx, [0 5],5,.5);
[x2,y2]=eulode(dydx,[0 5],5,.1);
[x3,y3]=eulode(dydx,[0 5],5,.01);
disp([x1,y1])
disp([x2,y2])
disp([x3,y3])
%%Percent Error
x1=0:.5:5;
x2=0:.1:5;
x3=0:.01:5;
analytical_step1= (-x1.^2+25).^(1/2)
analytical_step2=(-x2.^2+25).^(1/2);
analytical_step3=(-x3.^2+25).^(1/2);
numerical_1=[5.000 5.000  4.9500 4.8490 4.6943 4.4813 4.2024 3.8454 3.3903 2.8004 1.9970 ]
numerical_2=[5.0000 5.0000 4.9980 4.9940 4.9880 4.9800 4.9699 4.9579 4.9437 4.9276 4.9093 4.8889 4.8664 4.8418 4.8149 4.7858 4.7545 4.7208 4.6848 4.6464 4.6055 4.5621 4.5161 4.4673 4.4159 4.3615 4.3042 4.2438 4.1802 4.1132 4.0427 3.9685 3.8904 3.8081 3.7214 3.6301 3.5337 3.4318 3.3240 3.2096 3.0881 2.9586 2.8200 2.6711 2.5101 2.3348 2.1421 1.9273 1.6835 1.3984 1.0480];    
Percent_Error1=abs((analytical_step1-numerical_1)/analytical_step1)*100%answer displayed in percent
Percent_Error2=abs((analytical_step2-numerical_2)/analytical_step2)*100%answer displayed in percent

Answer 1

[bym]

Just use your definition of f to obtain all values at once (do not re-use variables like y1 etc):

Percent_Error1 = abs((y1-f(x1))./f(x1));

where x1 and y1 are outputs from your function eulode()

[Alagesan]

I just would like to know why the percent of error is used here? can I know why?

[Ella]

Is the answer pf this equation already in percentage or we still need to times it by 100 ?

[Image Analyst]

Looks to me like it's a fraction, so to get percentage you'd have to multiply by 100.

[dfsdf]

COMO MRD TE FUNCIONA EL COMANDO CAUSA PTMR

[dfsdf]

AYUDAME P

[dfsdf]

OE RES BOTAO

[Walter Roberson]

@dfsdf

Disculpas, pero Google tiene problemas para traducir "MRD" y "PTMR"