finding roots in a quadratic formula

im not entirely sure what i am doing wrong but this is the sciprt that i have written so far

function (x1, x2) = quad(a, b, c); 
z= sqrt(b^2 -4*a*c);
w= 2*a; 
x1= (-b+z)/w;
x2=(-b-z)/w; 
a= input('Enter a Value for a')
b= input('Enter a value for b')
c= input('enter a vlaue for c')
if z<<0
    fprintf('There are no real values')
else if z=0 
        fprintf('There is only one real root') 
    else z>>0 
            fprintf('There is two real roots') 
    end 

[Vladimir Sovkov]

(1) The discriminant is z=b^2 -4*a*c (no sqrt) - its sign matters;

(2) must be: line 9 ...z<0, line 11 ...z==0, line 13 z>0;

(3) if you transfer a, b, c as the function arguments, why do you use the "input" commands for them later? Their values renewed with "input" are never used.

Answer 1

[KALYAN ACHARJYA]

function [z,x1,x2]=quad(a,b,c) 
z=sqrt(b^2 -4*a*c);
w=2*a; 
x1=(-b+z)/w;
x2=(-b-z)/w; 
end

Call the quad function in Main Script:

a=input('Enter a Value for a: ');
b=input('\nEnter a value for b: ');
c=input('\nEnter a vlaue for c: ');
[z,x1,x2]=quad(a,b,c);
if z<0
    fprintf('There are no real values')
elseif z==0 
    fprintf('There is only one real root') 
else 
    fprintf('There is two real roots') 
end 

[STUDENT]

the program wont run it says

Error: File: quad.m Line: 9 Column: 1

This statement is not inside any function.

(It follows the END that terminates the definition of the function "quad".)

[KALYAN ACHARJYA]

Save the function file in another Matlab file named as quad.m and call that function from main script, it OK (no coding error).