How to format the Numbers in Output

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Jacob
Jacob 2012-4-8
评论： AKSHAY SAXENA 2018-1-27
Hi Everyone. I have written a short code to perform Langrange Interpolation. The code works fine in giving the numerical results; however, I am wondering if one may help on how to format how the Langrange function appears on the results. I wish it doesnt display the number in such long format as shown below in the code:
clear all
clc
format short e
syms xx x
fx = sin(exp(x)-2);
x = linspace(0,2,7);
y = subs(fx,x);
n =6;
sum = 0;
for i = 1:n+1
product = y(i);
for j = 1:n+1
if i~=j
product = product*(xx-x(j))/(x(i)-x(j));
end
end
sum = sum+product;
end
langrange = sum
f = subs(langrange,x);
E = y-f;
Results = [x' y' f' E']
Here is what I get as results. Notice that the numerical part is fine:
langrange =
(133340683792790313*xx*(xx - 1)*(xx - 2)*(xx - 1/3)*(xx - 2/3)*(xx - 4/3))/144115188075855872 + (2134614566129670693*xx*(xx - 1)*(xx - 2)*(xx - 1/3)*(xx - 2/3)*(xx - 5/3))/144115188075855872 - (914760085722758757*xx*(xx - 1)*(xx - 2)*(xx - 1/3)*(xx - 4/3)*(xx - 5/3))/1152921504606846976 + (1243774911652968393*xx*(xx - 1)*(xx - 2)*(xx - 2/3)*(xx - 4/3)*(xx - 5/3))/360287970189639680 - (56882977377095097*xx*(xx - 1)*(xx - 1/3)*(xx - 2/3)*(xx - 4/3)*(xx - 5/3))/72057594037927936 - (480132804261592377*xx*(xx - 2)*(xx - 1/3)*(xx - 2/3)*(xx - 4/3)*(xx - 5/3))/36028797018963968 - (27*((11368945240871781*xx)/4503599627370496 - 3789648413623927/4503599627370496)*(xx - 1)*(xx - 2)*(xx - 2/3)*(xx - 4/3)*(xx - 5/3))/80
Results =
0 -8.4147e-001 -8.4147e-001 0
3.3333e-001 -5.6826e-001 -5.6826e-001 1.1102e-016
6.6667e-001 -5.2242e-002 -5.2242e-002 1.3878e-017
1.0000e+000 6.5809e-001 6.5809e-001 0
1.3333e+000 9.7527e-001 9.7527e-001 -2.2204e-016
1.6667e+000 -1.5230e-001 -1.5230e-001 5.5511e-017
2.0000e+000 -7.7966e-001 -7.7966e-001 0
Any help would be appreciated. Thank you for your time.

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采纳的回答

Walter Roberson
Walter Roberson 2012-4-8
Perhaps
vpa(langrange)
By the way, please do not name your variable "sum": that conflicts with the name of the routine "sum", and conflicts like that often lead to trouble that is difficult to diagnose.
  2 个评论
Jacob
Jacob 2012-4-8
I had the method working but is there a way of reducing the number of decimal points? I tried to do "format shortE" at the beginning to display every number with only 4 decimal numbers; however, it works ony for the numerical results, for the Langrange functions it displays up to 30 decimal points.

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