Calculating values from an iterative map

I need to write a Matlab code that will calculate the x10 value for the following iterative map that doesn't use fsolve,\ or inv commands, given x0= -3.

I also need a code that will calculate:

for the same iterative map.

Any help would be very appreciated :)

[Ollie]

Thanks, I think I understand how to do the first part now although I am still struggling with the second part. Is there anyone who could give me the specific code to program it?

Answer 1

[Walter Roberson]

Use a "for" loop. Inside the "for" use "if" and "elseif".

[Walter Roberson]

x(1) = 0;
 for n = 1 : 10
   xn = x(n);
   first_expression = some calculation with xn
   second_expression = some other calculation with xn
   if first_expression < second_expression
     xn1 = some result calculated with xn
   else
     ....
     if third_expression < fourth_expression
        ...
        xn1 = ...
     else
       ...
       xn1 = ....
     end
   end
   x(n+1) = xn1
 end

[Ollie]

Thanks for the reply. This is the code I have attempted:

 x(1)=-3;
for n = 1:10
    xn = x(n);
    expression1 = xn^4 + 8;
    expression2 = 1/(xn*sqrt(abs(xn)));
    expression3 = 3 - xn^2; 

    if expression1 <= expression2
        xn1 = sqrt(abs(xn)) - 3*xn
    else
        if expression3 <= expression2
        xn1 = -1/xn*tan(xn)
    else
        xn1 = -3/xn
        end
    end
    x(n+1)=xn1
end

The code is not returning the correct result. Can you tell me how to fix it?

Answer 2

[Purushottama Rao]

for the second part,

s=0;
for n=4:8
k=(x(n-1)-2)+(x(n-1)+1);
s=s+k;
end 
disp(s)

[Ollie]

Thank you