Indexing array element with for loop with specified step size

Hi MATLAB users,

I have a data file for 1 row and 332 columns. The first column correspond to time vale and rest 331 coliumns correspond to coordinate values of atoms of a molecule. I want to multiply each atom by certain value to get my output. But since my column numbers are odd, I am not able to specify the exact step size in the for loop.

Example,

My input file looks like the following

|<- Molecule 1 ->| |<- Molecule 2 ->| ................ <- Molecule 331->

Time_value ATOM1 ATOM2 ATOM3 ATOM4 ATOM1 ATOM 2ATOM3 ATOM4.....................

I have to multiply ATOM1 by 2, ATOM2 by 3, ATOM3 by 5 and ATOM4 by 8.

Following is my code:

for i = 2:4:331

X = 2*ATOM1 + 3*ATOM2 + 5*ATOM3 + 8*ATOM4;

end

I am not able to get the correct output as desired.

It will be very nice if anyone can help me.

Thanks in advance !

[Cris LaPierre]

How is your data stored in each column? You example suggests that each of the 331 columns contain 4 atom coordinates. Is that correct?