Doing calculation across columns

Hi there. I have a 4 column by 500 row matrix. How would I add a fifth column that calculates , where x is the corresponding value in the second column across the same row.

Thanks!

Answer 1

[madhan ravi]

D=zeros(500,5);
D=matrix;
D(:,5)=exp((-(matrix(:,2)-75)/2).^2)

[Jenny Hall]

I am currently trying to do something similar, in order to carry out a calculation of every value in one column. This code I have written is as follows:

x(:,2) = (((6.64e-34)*(9.5e+9))/((9.274e-24)*(x(:,1)/10000)))

However this only seems to calculate a value for the final row in the column, whilst all of the values come out as 0. The column contains 1024 rows.

Any help would be much appreciated!

[Stephen23]

x(:,2) = (((6.64e-34)*(9.5e+9))./((9.274e-24)*(x(:,1)/10000)))
%                              ^^ you might want array division here

https://www.mathworks.com/help/matlab/matlab_prog/array-vs-matrix-operations.html

[Jenny Hall]

Thank you! This worked a treat.

Answer 2

[JULIEN BARBAUD]

I think that if you call your input matrix A, and the final result B, then this:

f=@(x) exp( (-(x-75)/2).^2 )
 
 B=[A f(A(:,2))];

should do the trick

EDIT: oops, madhan was quicker