Notimplemented GE function

Hi,

I am trying to sum alle positive value's in a vector.

Im trying this by;

A=([1;1;-1;-1])

For i=1:4
if A(i,1)>=0
sum(A(i,1))
end
end

But it doesnt work, GE is not implemented, i have a student version sow..

Anyone has an alternitive?

I will have a vector with appr. 8000 rows with data, is there an easy way to analyse this data?

Answer 1

[Andrew Newell]

sum(A(A>=0))

EDIT: better still,

sum(A(A>0)

Answer 2

[Walter Roberson]

I suspect your actual code has

A = {[1;1;-1;-1]};

or

A = {1;1;-1;-1};

If so then A is a cell array, and A(i,1) is a cell array, and > is not defined for cell arrays. To access the content of A(i,1) in such a case, you would use A{i,1}

Answer 3

[Andrew Newell]

I should add that your code doesn't work because it has some errors in it, not because GE is not implemented. A version that is similar to yours but works is

A=([1;1;-1;-1]);

AposSum = 0;
for i=1:4
if A(i,1)>=0
AposSum = AposSum + A(i,1);
end
end
AposSum

Answer 4

[Frank]

How do i know if it is a cell/array/matrix or something?

It has in the workspace a Cube in front of it, re.. Could it be called " Tensile Data"?

I think i am doing something wrong with writing my data... I tried a lot..

Isnt it possible to export it to a Txt file and then read it in again?

Thanks in advance!

[Andrew Newell]

Look at the Value column, to the right of Name. It should say something like <8000x1 cell> or [8000x1 double]. If it's the latter, you should be able to use my method.

[Andrew Newell]

If you're still not sure, type "whos A" and paste the answer in your question.

Answer 5

[Andrew Newell]

If Walter is right and it's a cell array, you could do this:

ipos = [A{:}]>0;
if any(ipos)
  Asum = sum(A{ipos});
else
  Asum = 0;
end

That funny looking first line extracts the values of A using A{:} and then puts it in a double array using [].

Answer 6

[Frank]

I solved it!

B=double(A) makes the matrix numeric or something like that, now i can do everything i want with it!

Anyways, thank u all for the help!

[Andrew Newell]

So what type was it before?

[Walter Roberson]

If double() worked to make it numeric, then it must have been symbolic.

[Andrew Newell]

That would also explain the problem with GE.