How to change the answer into decimals

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Faris Sulam
Faris Sulam 2021-1-25
编辑： VBBV 2021-1-25
Hi all,
I wanted to ask about my result here. Usually it is in decimals but when i used poly2sym here it turned into fractions. How can I change it back to decimals? Thanks in advance
  2 个评论
Birdman
Birdman 2021-1-25
Can you share your entire code? It is hard to tell what you tried to do here.
Faris Sulam
Faris Sulam 2021-1-25
So i was basically trying to convert the answer of the folloing code into a polynomial form:
function [ p ] = UDPolyReg( x,y )
%UNTITLED2 Summary of this function goes here
% Detailed explanation goes here
%y=[0 3 4.5 5.8 5.9 5.8 6.2 7.4 9.6 15.6 20.7 26.7 31.1 35.6 39.3 41.5]
n=length(x);
m=4;
for i=1:2*m
xsum(i)=sum(x.^(i));
end
a(1,1)=n
b(1,1)=sum(y)
for j=2:m+1
a(1,j)=xsum(j-1);
end
for i=2:m+1
for j=1:m+1
a(i,j)=xsum(j+i-2);
end
b(i,1)=sum(x.^(i-1).*y);
end
p=(a\b)'
for i=1:m+1
FuncVal(i)=p(m+2-i);
end
Vstrain=0:0.1:6;
stressfit=polyval(FuncVal,Vstrain);
plot(x,y,'ro',Vstrain, stressfit)
xlabel('Strain')
ylabel('Stress')
end

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采纳的回答

VBBV
VBBV 2021-1-25
编辑：VBBV 2021-1-25
poly2sym converts numeric vector to vector of symbolic equation and by default it uses the variable x. The values in vector are treated as coefficient of symbolic polynomial in x.
  1 个评论
VBBV
VBBV 2021-1-25
编辑：VBBV 2021-1-25
In your case vector has 5 values. So it results in polynomial in 4th power. MATLAB converted the numeric values to fractions and expressed in form of polynomial.
Use sym2poly to convert back to numeric vector.

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