need mfile for my non linear system

I have to employ the newton raphson algorithm to solve my equations,. I need to create a function m-file to do so. This is my first matlab assignment and I'm not really familiar with it. I don't really know how to go about the iteration and I try to write it but matlab not solve. this is my try. Any help would be greatly appreciated.

[Walter Roberson]

It is disappointing that the user deleted nearly all of their comments from the extended discussion, making it difficult to follow the conversation. The volunteers give their time with an understanding that the discussion will remain public and so be of value to anyone else who looks. When important parts of the discussion are removed then the volunteers tend to start to feel as if they have been taken advantage of.

[Walter Roberson]

hasan s: I notice that you unaccepted Cris's answer, indicating that another answer was better. Could you post a link to the place where you received the better response?

[hasan s]

It has been discovered that the question I asked contains errors

The program has been canceled due to a mistake in the question

I deleted it so as not to affect the followers because my question is wrong

Your valuable suggestions remain.

Thanks for your efforts

[Walter Roberson]

However, our solution is for the question as posted, and is useful for people who might want to study the techniques.

It is not uncommon for people to discover that they made a mistake in asking the question when they start thinking about the responses they got. It is also not uncommon that when users see how the volunteers interpret the question that was actually asked, that the user's thought processes are pulled out of the grove they were in, and are able to see how they should have proceeded. Thus, even questions containing mistakes are valuable to readers. Indeed, most questions that are posted contain a mistake of some sort, and figuring out what the mistake is is a lot of what we do here.

Answer 1

[Cris LaPierre]

You can find examples and explanations about how to create a funciton file here:

https://www.mathworks.com/help/matlab/matlab_prog/create-functions-in-files.html

[Cris LaPierre]

I'm not going to write it for you, but if you ask specific questions, I'm happy to answer them.

[Cris LaPierre]

Before you use a variable on the right side of an equals sign, you have to define it.

% Define a variable x
x=5;
% This works because x has been defined
y=2*x

y = 10

% This does not because z has not been defined
y=2*z

Unrecognized function or variable 'z'.

If you are new to programming in MATLAB, I suggest going through MATLAB Onramp. This will introduce you to the fundamentals in an interative way and at your own pace.

[Cris LaPierre]

That's a warning, not an error. You can ignore that for now.

Onramp will take you ~2 hours. Given the date and the urgency of your assignment, that is going to be 2 hours well spent.

[Cris LaPierre]

1. Complete MATLAB Onramp
2. Ignore the message about B. This is not an error.

[hasan s]

please, if you can

what mean Onramp

[Jan]

"Onramp" means the online Matlab lesson to learn the basics: https://www.mathworks.com/learn/tutorials/matlab-onramp.html

[Cris LaPierre]

Ch 2 Task 5 in MATLAB Onramp.

Remove the semicolon at the end of each statement you would like to see the command window.

[Walter Roberson]

In order for results to appear, you need to use one of a few different possibilities:

• disp(expression) to have the results of the expression displayed; or
• fprintf(format, expression) to have the results of the expression displayed as text in a more controlled way; or
• have a calculation expression that is not followed by semi-colon

F = randi([-40 99]);
disp(F)              %example of disp

   -27

fprintf('Temperature in Fahrenheit is %g\n', F);    %example of fprintf

Temperature in Fahrenheit is -27

C = (F-32)*5/9       %example of no semi-colon

C = -32.7778

[hasan s]

Thank you very much for all the reply

I do all that , but the result not appear

[Walter Roberson]

Your file name has a space in it. Untitled 33.m . You need to remove the space.

x=[B(i)+G(i)*(gamma(1+1/A(i)))-sum1;(G(i)^2)*(gamma(1+2/A(i))) 
+(2*B(i)*G(i)*gamma(1+1/A(i)) 
+B(i)^2-sum2);(G(i)^3*gamma(1+3/A(i))+3*B(i)*G(i)^2*gamma(1+2/A(i))+3*G(i)*B(i)^2*gamma(1+1/A(i))+B(i)^3-sum3)]; 

MATLAB does not continue lines automatically (unlike C, for example).

x=[B(i)+G(i)*(gamma(1+1/A(i)))-sum1;(G(i)^2)*(gamma(1+2/A(i)))
    1 0  1 0 1     2     3 320

so the part up to the ; is a valid complete element, and the ; explicitly marks the end of a row

x=[B(i)+G(i)*(gamma(1+1/A(i)))-sum1;(G(i)^2)*(gamma(1+2/A(i)))
                                    1 2 1  0 1     2     3 210

so the (G to end of line is a valid complete element. Inside [], when a line ends with no continuation symbol, that is treated as an implicit end of row, as if you had written a ; at the end of the line. Thus, the above line of code gives two complete matrix rows.

 +(2*B(i)*G(i)*gamma(1+1/A(i)) 
  1   2 1  2 1      2     3 21      <== missing )

You are inside [] so MATLAB will try to treat that as a matrix row. However, it is missing a ) to be a valid matrix row. The + at the beginning of the line is not a problem: it is treated as a "unary plus". Just the same way that you can write -5 to indicate 0 minus 5, or -x to indicate 0 minus x, you can write +5 to indicate 0 plus 5, or +x to indicate 0 plus x. In this context, the + does not signal that you are in the middle of an addition.

+B(i)^2-sum2);(G(i)^3*gamma(1+3/A(i))+3*B(i)*G(i)^2*gamma(1+2/A(i))+3*G(i)*B(i)^2*gamma(1+1/A(i))+B(i)^3-sum3)]; 
  1 0       !

Again, the + at the beginning of the line is valid unary operation and does not signal that you are in the middle of an addition. But then you have one extra ) on the matrix element.

What you probably wanted was

x=[B(i)+G(i)*(gamma(1+1/A(i)))-sum1;(G(i)^2)*(gamma(1+2/A(i)))... 
+(2*B(i)*G(i)*gamma(1+1/A(i))...
+B(i)^2-sum2);(G(i)^3*gamma(1+3/A(i))+3*B(i)*G(i)^2*gamma(1+2/A(i))+3*G(i)*B(i)^2*gamma(1+1/A(i))+B(i)^3-sum3)];

which in turn would be better written

x=[B(i)+G(i)*(gamma(1+1/A(i)))-sum1;
   (G(i)^2)*(gamma(1+2/A(i)))+(2*B(i)*G(i)*gamma(1+1/A(i))+B(i)^2-sum2);
   (G(i)^3*gamma(1+3/A(i))+3*B(i)*G(i)^2*gamma(1+2/A(i))+3*G(i)*B(i)^2*gamma(1+1/A(i))+B(i)^3-sum3)];

We are not able to test the code as you did not initialize T or G or B or A.

Also

Program (2)

You should probably be storing the second program in its own file.

[Walter Roberson]

Your code uses i a lot, and stores into

A(i+1)=z(1); 
B(i+1)=z(2); 
G(i+1)=z(3); 

but the only place it changes i is right at the beginning, before the loop, where you have the unusual lines

i=0;  
i=i+1;  

In your second batch of code, you use Psi but you do not initialize it. Perhaps you wanted psi

In your first program

q=inv(d);

You have a problem because d becomes nearly singular.

[Walter Roberson]

I did not write gamma "instead" of anything. Your code had

x=[B(i)+G(i)*(gamma(1+1/A(i)))-sum1;(G(i)^2)*(gamma(1+2/A(i))) 
+(2*B(i)*G(i)*gamma(1+1/A(i)) 
+B(i)^2-sum2);(G(i)^3*gamma(1+3/A(i))+3*B(i)*G(i)^2*gamma(1+2/A(i))+3*G(i)*B(i)^2*gamma(1+1/A(i))+B(i)^3-sum3)]; 

which already has gamma in it. I reformatted,

x=[B(i)+G(i)*(gamma(1+1/A(i)))-sum1;
    (G(i)^2)*(gamma(1+2/A(i)))+(2*B(i)*G(i)*gamma(1+1/A(i))+B(i)^2-sum2);
    (G(i)^3*gamma(1+3/A(i))+3*B(i)*G(i)^2*gamma(1+2/A(i))+3*G(i)*B(i)^2*gamma(1+1/A(i))+B(i)^3-sum3)]; 

which is just moving around the line breaks.

q=inv(d); 
p=q*x;

cannot be replaced by x/d but can be replaced by

p=d\x;

No,

A(i+1)=z; 
B(i+1)=z; 
G(i+1)=z; 

is not a replacement for the existing lines. z is a vector of length 3, but A(i+1) only designates a single output location. You also want A, B, and G to get different outputs, but assigning z to all of them would give the same value to each.

What you could do is

zcell = num2cell(z(1:3));
[A(i+1), B(i+1), G(i+1)] = zcell{:};

but this is less clear than just doing three assignment statements.

T=1;
A=2;
B=3;
G=4;

That will not work. You have

for j=1:50 
sum1=sum1+log((T(j)-B(i))/G(i)); 

When j becomes 2, you need to access T(2) but T has only been initialized as a scalar. You never store into T after the initial assignment.

[hasan s]

THANK YOU VERY MUCH