how can i correct this code and get rid of error? urgent help please

Question

Ilkay Köse 2022-1-22

0
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此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/1633860-how-can-i-correct-this-code-and-get-rid-of-error-urgent-help-please

评论： Image Analyst 2022-1-22

fprintf('\n The equation by Lagrange is:\n');

yvalue

fprintf('\n The answer for part c\n');

fprintf('The value of Volume at 1.05 bar by Lagrange is %f m^3\n',vpa(subs(yvalue,xvalue,x)));

fprintf('\n The answer for part d\n');

fprintf('\n The absolute difference between volume by predicted model and Lagrange interpolation is %f m^3\n',abs((A(1)*exp(A(2)*x))-(vpa(subs(yvalue,xvalue,x)))));

end

i wrote this code for my homework but gives error in bold underlined line. how can i correct it. i use Matlab R2013a . thank you.

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Ilkay Köse 2022-1-22

this is my full code:

function [a0,a1]=work(x,xvector,fvector)

fun=@(X,xdata) X(1)*exp(X(2)*xdata);

X0=rand(1,2);

A=lsqcurvefit(fun,X0,xvector,fvector);

fprintf('\n The answer for part a\n');

fprintf('\n V=%fe^(%f*P) \n',A(1),A(2));

fprintf('\n The answer for part b\n');

fprintf('The value of Volume at 2.5 bar by model is %f m^3\n',A(1)*exp(A(2)*x));

%Lagrange Method

syms xvalue

yvalue=0;

for i=1:length(xvector)

p=1;

for j=1:length(xvector)

if i~=j

p=p*((xvalue-xvector(j))/(xvector(i)-xvector(j)));

end

yvalue=yvalue+(p*fvector(i));

end

fprintf('\n The equation by Lagrange is:\n');

yvalue

fprintf('\n The answer for part c\n');

fprintf('The value of Volume at 1.05 bar by Lagrange is %f m^3\n',vpa(subs(yvalue,xvalue,x)));

fprintf('\n The answer for part d\n');

fprintf('\n The absolute difference between volume by predicted model and Lagrange interpolation is %f m^3\n',abs((A(1)*exp(A(2)*x))-(vpa(subs(yvalue,xvalue,x)))));

end

and this is the error:

Error using fprintf

Function is not defined for 'sym' inputs.

Error in work (line 24)

fprintf('The value of Volume at 1.05 bar by Lagrange is %1.05f

m^3\n',vpa(subs(yvalue,xvalue,x)));

Image Analyst 2022-1-22

Duplicate post:

https://www.mathworks.com/matlabcentral/answers/1633875-the-code-gives-error-can-you-help-me-to-correct-it-i-really-do-need-help?s_tid=srchtitle

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Answer 1

Simon Chan 2022-1-22

0
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此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/1633860-how-can-i-correct-this-code-and-get-rid-of-error-urgent-help-please#answer_879510

You need to specify the number of digits after the decimal point.

For example, %.2f or %.4f for 2 and 4 digits after the decimal point respectively.

%f states nothing and give you an error

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Ilkay Köse 2022-1-22

still gives error. this is my full code:

function [a0,a1]=work(x,xvector,fvector)

fun=@(X,xdata) X(1)*exp(X(2)*xdata);

X0=rand(1,2);

A=lsqcurvefit(fun,X0,xvector,fvector);

fprintf('\n The answer for part a\n');

fprintf('\n V=%fe^(%f*P) \n',A(1),A(2));

fprintf('\n The answer for part b\n');

fprintf('The value of Volume at 2.5 bar by model is %f m^3\n',A(1)*exp(A(2)*x));

%Lagrange Method

syms xvalue

yvalue=0;

for i=1:length(xvector)

p=1;

for j=1:length(xvector)

if i~=j

p=p*((xvalue-xvector(j))/(xvector(i)-xvector(j)));

end

yvalue=yvalue+(p*fvector(i));

end

fprintf('\n The equation by Lagrange is:\n');

yvalue

fprintf('\n The answer for part c\n');

fprintf('The value of Volume at 1.05 bar by Lagrange is %f m^3\n',vpa(subs(yvalue,xvalue,x)));

fprintf('\n The answer for part d\n');

fprintf('\n The absolute difference between volume by predicted model and Lagrange interpolation is %f m^3\n',abs((A(1)*exp(A(2)*x))-(vpa(subs(yvalue,xvalue,x)))));

end

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