extrema

clc%removes command window
clear all%removes workspace
close all%clears pics and graphs
syms x real
f= input('Enter the function f(x):');
fx= diff(f,x)
c = solve(fx)
cmin = min(double(c));
cmax = max(double(c));
ezplot(f,[cmin-2,cmax+2])
hold on
fxx= diff(fx,x)
for i = 1:1:size(c)
    T1 = subs(fxx, x ,c(i) );
    T3= subs(f, x, c(i));
 if (double(T1)==0)
    sprintf('The point x is %d inflexion point',double (c(i))) 
    else
       if (double(T1) < 0)
    sprintf('The maximum point x is %d', double(c(i))) 
    sprintf('The value of the function is %d', double (T3))
       else
    sprintf('The minimum point x is %d', double(c(i)))  
            sprintf('The value of the function is %d', double(T3))
       end 
 end
plot(double(c(i)), double(T3), 'r*', 'markersize', 15); 
end
pause
h=ezplot(fx,[cmin-2,cmax+2])
set(h,'color','r')
hold on
pause
e=ezplot(fxx,[cmin-4,cmax+4])
set(e,'color','g')
hold off