2. Write a Matlab program that will allow the user to enter the coefficients of

Question

2. Write a Matlab program that will allow the user to enter the coefficients of a polynomial and make some calculations. Selections and data entry will be done by presenting the user with a menu (using menu function) and provide her/him with the following choices:

Enter the degree and coefficients of the polynomial

Evaluate the polynomial at a user defined point

Display the roots of the polynomial

Exit

Other Requirements:

Selecting choice 2 and 3 before entering the degree and coefficients will result in an error message. The program will terminate only when Exit has been selected

Calculations will be done by functions.

o Function polynomial() will ask for the degree and the coefficients of the polynomial and would return the coefficients.

o Function polyEval() will accept a parameter, the evaluation point, and returns the value of the polynomial at that point.

o Function polyRoots() will accept the coefficients and returns the roots.

Results are displayed with 2 decimal place accuracy.

Help with coefficient entry:

%store the coefficients of the polynomial that have been entered

% in a vector. Return coefficients as a vector called p

%this vector should be global so that other functions can use it

global p;

p=[]; %creates an empty polynomial

degree=input('Please enter the degree of the polynomial: ');

j=degree; %this is used for correct message display below

degree=degree+1;

for i=1:1:degree

fprintf('Please enter the coefficient of power %d ',j);

p(i)=input(' ');

j=j-1;

end

%note the highest degree coefficient is stored in position 1

%and the next one is position 2 and so on.

Explanation / Answer

%Matlab program to evaluate and display the roots of a polynomial
clear
choice=-1:
s=0:
global p[];
while choice < 4 do
choice = menu('Select your choice','Enter the degree and coefficients of the polynomial',
'Evaluate the polynomial at a user defined point','Display the roots of the polynomial','Exit');
switch(choice)
case 1
s=1;
polynomial();
  
case 2
pt=input('Please enter the evaluation point: ');
if s==1
pvalue=polyEval(pt);
   disp('polynomial value at evaluation point:' )
   disp(pvalue)
   else
   break
case 3
if s==1
roots=polyRoots(p);
   disp('Roots of the polynomial:' )
   disp(roots)
   else
   break
case 4
exit
otherwise
fprintf('Invalid input ' );
   break
end
end_while
end

function p[] = polynomial()
degree=input('Please enter the degree of the polynomial: ');
j=degree; %this is used for correct message display below
degree=degree+1;
for i=1:degree
p(i)=input(Please enter the coefficient of power %d ',j);
j=j-1;
end
end

function pval = polyEval(epoint)
pval=polyval(p,epoint);
end

function root = polyRoots(p)
root=roots(p);
end

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