display function does not show the exact value

I am new to MATLAB. I wrote code like this;
syms n
f(n) = 40*n.^1.5-875*n+35000;
fdiff(n) = diff(f(n));
x0 = 100;
xprev = 0;
while (abs(x0 - xprev)/x0)*100 >= 1
xprev = x0;
x0 = x0 - f(x0)/fdiff(x0);
end
display(x0);
When I tried to display the value of x0, it shows;
600/11 - (40*(600/11 - ((24000*11^(1/2)*600^(1/2))/121 - 140000/11)/((60*11^(1/2)*600^(1/2))/11 - 875))^(3/2) + (875*((24000*11^(1/2)*600^(1/2))/121 - 140000/11))/((60*11^(1/2)*600^(1/2))/11 - 875) - 140000/11)/(60*(600/11 - ((24000*11^(1/2)*600^(1/2))/121 - 140000/11)/((60*11^(1/2)*600^(1/2))/11 - 875))^(1/2) - 875) - ((24000*11^(1/2)*600^(1/2))/121 - 140000/11)/((60*11^(1/2)*600^(1/2))/11 - 875)
Instead of just;
62.6913
How can I make it to display only the final value?

2 comentarios

Andreas Sorgatz
Andreas Sorgatz el 21 de Mzo. de 2016
The answer is a representation of the "exact" value. However, you can get an approximation of this exact result using vpa(...) if you need high precision or using double(...) if hardware precision is fine.
I fixed it with disp(vpa(x)), which gives you 32 digits of precision. Newton-Raphson function analysis here 2 :D

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Más respuestas (1)

John BG
John BG el 27 de Feb. de 2016
Mustafa
If you are really after a numeric result, why don't start with numeric values?
x_range=10
x_step=.1
x=[0:x_step:x_range]
f=@(x) 40*x.^1.5-875*x+35000
y=f(x)
ydiff = diff(y)
x0 = 100
xprev = 0
while (abs(x0 - xprev)/x0)*100 >= 1
xprev = x0
x0 = x0 - f(x0)/ydiff(x0)
end
x0 =
-82.29
Play with x_range and x_step to center the curve wherever you need.
If you find this answer of any help solving this question, please click on the thumbs-up vote link,
thanks in advance
John

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