convert number in a matrix to a scalar

Hello everyone I have matrix "values" and I need to sum all of it's element so I use sumOFvalues= sum(values(:)); the sumOFvalues is a matrix and I need to convert it into a scalar so I can addit with any number independent of the size. does any one know how to do this ?

thanks

[Stephen23]

@Reema Alhassan: please upload your data matrix in a .mat file, by clicking the paperclip button.

[Reema Alhassan]

i have attached it

[Stephen23]

@Reema Alhassan: in your uploaded Mfile you use sprintf to convert the maximum values into a char vector. But then confusingly there is a comment which states "i need the sumOfValues to be a scalar (double)": if you want sumOfValues to be a scalar double, why are you using sprintf to convert that scalar numeric to a character vector?

[Reema Alhassan]

sorry I didn't realized that

I used spring if to change the number format I need it to be in a decimal form for example 15565667.224455

not like this 233+e

[Stephen23]

@Reema Alhassan: numeric data types do not store any formatting information. How any numeric looks is irrelevant to how it is stored in memory. Converting your scalar numeric to a char vector is not likely to help you.

Answer 1

[Walter Roberson]

The bug is your line

sumOfValues=sprintf('%f', sumOfValues);

sprintf() formats numeric values as character vectors and returns the character vector. The output of the sprintf() is not a number: it is a character vector. In your case it happens to be a character vector containing 15 characters, '10765655.982710', which is the vector ['1' '0' '7' '6' etc] .

You are then writing over your original numeric value with that character vector.

What was your intent in using sprintf() at that point in your code?

[Reema Alhassan]

sorry I didn't realized that

I used sprintf() to change the number format I need it to be in a decimal form for example 15565667.224455

not like this 233+e

[Walter Roberson]

At the MATLAB command line give the command

format long g

and then display the numeric value again.

[Reema Alhassan]

thank you!

Answer 2

[Ameer Hamza]

What you are doing is correct, it should return a scalar value. For example

values = randi(5, 3, 3)
values =
   2     4     1
   4     1     1
   1     2     5
sumOfValues = sum(values(:))
sumOfValues =
  21

[Walter Roberson]

A matrix of results would have been returned if you had forgotten the (:) -- if you had used sum(values) for example.

[Ameer Hamza]

@Reema In MATLAB a 1x1 matrix is a scalar. There is no separate class type scalar in MATLAB.

[Ameer Hamza]

Can you give an example of what is not working. Because the syntax is fine. Except if you forget (:) as pointed by Walter.

[Jan]

@Reema Alhassan: It sounds like a misunderstanding. 1x1 matrices are scalars in Matlab. There is no difference:

a = 5
size(a)
% [1 1]