How do I make the following a function?

A =rand(1,100);
    % Christopher Clarke
    % 10/05/2020
    % This function calculates the mean and standard deviation without
    %   using in-built functions
    % M is the mean 
    % VSD is the Standard Deviation 
som=0;
for i=1:length(A)
  som=som+A(i);
end
M=som/length(A);
    % Above is the calculation for the mean 
moy=0;
for i=1:length(A)
    moy = (A(i)-M)^2;
    moy = sqrt((moy)/length(A)); 
end
VSD=moy/length(A); 
 % Above is the calculation for the Standard deviation 

Answer 1

[Walter Roberson]

Before any of that code, insert the line

function Christopher_Clarke_mean_and_standard_deviation

and store it in file Christopher_Clarke_mean_and_standard_deviation.m

[Christopher Clarke]

i am earning as i go so i aplogies in advance if i ask an obvious question.

How do i call the function to accept any N numbers?

[Walter Roberson]

How do i call the function to accept any N numbers?

function Christopher_Clarke_mean_and_standard_deviation(A)

and pass in the numbers when you call the function

Christopher_Clarke_mean_and_standard_deviation([1, 2, 4, 5, 6])

Answer 2

[KSSV]

[M,VSD] = myfunction(A) ; 
    % Christopher Clarke
    % 10/05/2020
    % This function calculates the mean and standard deviation without
    %   using in-built functions
    % M is the mean 
    % VSD is the Standard Deviation 
som=0;
for i=1:length(A)
  som=som+A(i);
end
M=som/length(A);
    % Above is the calculation for the mean 
moy=0;
for i=1:length(A)
    moy = (A(i)-M)^2;
    moy = sqrt((moy)/length(A)); 
end
VSD=moy/length(A); 
 % Above is the calculation for the Standard deviation 

Save the above function...

 A = rand(1,100) ; 
 [mu,sd] = myfunction(A) ; 

[Christopher Clarke]

Hi,

Thank you for responding, when i tried this i got an error even when i created a new function file. Am i doing something wrong?

[KSSV]

What error you got?

[Walter Roberson]

What error are you getting?

Note: the code will have problems if A is not scalar or vector.

[Christopher Clarke]

function Christopher_Clarke_mean_and_standard_deviation
A =rand(1,100);
    % Christopher Clarke
    % 10/05/2020
    % This function calculates the mean and standard deviation without
    %   using in-built functions
    % M is the mean 
    % VSD is the Standard Deviation 
som=0;
for i=1:length(A)
  som=som+A(i);
end
M=som/length(A);
    % Above is the calculation for the mean 
moy=0;
for i=1:length(A)
    moy = (A(i)-M)^2;
    moy = sqrt((moy)/length(A)); 
end
VSD=moy/length(A); 
 % Above is the calculation for the Standard deviation 

[KSSV]

A = [1 2 4 5 6] ;
[mu,sd] = myfunction(A) ; 

I have mentioned you already how to call the function.

If you follwed what is hown in the image..use

Christopher_Clarke_mean_and_standard_deviation([1 2 4 5 6]) 

[Walter Roberson]

function Christopher_Clarke_mean_and_standard_deviation(A)
A = rand(1,100);
    % Christopher Clarke
    % 10/05/2020
    % This function calculates the mean and standard deviation without
    %   using in-built functions
    % M is the mean 
    % VSD is the Standard Deviation 
som = 0;
for i=1:length(A)
  som = som + A(i);
end
M = som/length(A);
    % Above is the calculation for the mean 
moy = 0;
for i=1:length(A)
    moy = (A(i)-M)^2;
    moy = sqrt((moy)/length(A)); 
end
VSD = moy/length(A); 
 % Above is the calculation for the Standard deviation

This will accept a single argument, but will then promptly ignore it and over-write it with the random values.

You need to make a decision: will the A matrix be generated inside the function, or will it be something that you accept as a parameter?

Another note:

 Christopher_Clarke_mean_and_standard_deviation [1,2,4,5,6]

In MATLAB, when you name a function as the first thing on a line, and then you have whitespace, and the next non-whitespace on the line is not open-bracket or comma or semi-colon, then MATLAB takes what is there as characters and passes in the characters to the command. The full rules about exactly when it stops taking characters is a bit complicated. Anyhow, the effect of the above would be that the character vector '[1,2,4,5,6]' would be passed in to the function. In order to have what you type interpreted as numeric, you need to use () around it, like

  Christopher_Clarke_mean_and_standard_deviation([1,2,4,5,6])

Answer 3

[Christopher Clarke]

function Christopher_Clarke_mean_and_standard_deviation([1 2 4 5 6]) 
A =rand(1,100);
    % Christopher Clarke
    % 10/05/2020
    % This function calculates the mean and standard deviation without
    %   using in-built functions
    % M is the mean 
    % VSD is the Standard Deviation 
som=0;
for i=1:length(A)
  som=som+A(i);
end
M=som/length(A);
    % Above is the calculation for the mean 
moy=0;
for i=1:length(A)
    moy = (A(i)-M)^2;
    moy = sqrt((moy)/length(A)); 
end
VSD=moy/length(A); 
 % Above is the calculation for the Standard deviation 
 

[Christopher Clarke]

>> Christopher_Clarke_mean_and_standard_deviation

Error: File: Christopher_Clarke_mean_and_standard_deviation.m Line: 1 Column: 57

Invalid expression. When calling a function or indexing a variable, use parentheses. Otherwise, check for mismatched delimiters.

Abouve is the error message i get.

[Walter Roberson]

function Christopher_Clarke_mean_and_standard_deviation([1 2 4 5 6]) 
                                                       ^^^^^^^^^^^^^

At the place I point out in a function line, you are permitted one of several things:

1. Emptiness, as in the ([1 2 4 5 6]) not appearing at all, just function Christopher_Clarke_mean_and_standard_deviation
2. () with nothing inside, as in function Christopher_Clarke_mean_and_standard_deviation()
3. () with a list of items inside, separated by commas. Each item may be a plain unindexed variable name, or else the special indication ~ or the keyword varargin . For example |function Christopher_Clarke_mean_and_standard_deviation(A,~, varargin)

It is never valid to put a literal constant of any form inside the () on the function line, and it is never valid to put indexed variables there either.

The purpose of a function line is to establish a local name for whatever value is passed in by the user in the corresponding position. Putting something like [1 2 4 5 6] there does not establish any connection between a value passed in by the user and a local variable name.

It is also not possible to establish default values for input on the function line.