MATLAB

Given a (plain text!) file containing N columns of values, we need to read the values into matlab for exploration and plotting. To do this, we need to know the name of the file, and how data is arranged in it, so need to open it in a (plain text!) editor. Write a script "read.m" which:

1.) reads a given file "file.dat" into a matrix "mat",

2.) extracts the columns from "mat" into arrays "c1", "c2", ..., "cN",

3.) plots some column versus another column, with a title, and labeled axes.

To test and debug your code, create a "file.dat" with N=2 columns, each with 3 values ( so a 32 array ). The first column should be sorted. You can just enter some numbers in "file.dat" in an editor. Next, test it on a 43 array to make sure it also works. Insert brief comments to document what is being done.

To Do:

Download the file file.dat and save it as "file.dat" . View it in an editor to see its contents. The first two lines contain labels, need to be read over with fgetl . The rest of the lines are numerical values to be scanned into a matrix, say "mat". Plot columns 1 , 3 using Gnuplot: gnuplot> plot "prof300s.dat" u 1:3 w lines lw 2 Copy your "read.m" to "lab.m" and modify appropriately to achieve the following: a. Read the data into a matrix "mat". b. Extract each column into a vector (with sensible names: x , C , B , ... ). c. Find Bmax = maximum value of B, and at which index it occurs, iBmax. Set cut = Bmax/2 . d. Plot B vs x and the line at height cut, on the same plot. The units of x are micrometers (m). Note: Once you know the value of "cut", say 1.5, it's easy to do it in Gnuplot (outside Matlab): gnuplot> cut=1.5; plot "prof300s.dat" u 1:3 w lines lw 2 , cut lw 3 e. Is this value of cut a good choice here? does it really represent half-maximum of the bump ? (note that the "base" value of B is 1, not zero). Figure out a better expression for setting "cut". f. Now (copy and) modify your FWHM.m code (from previous lab), insert it into "lab.m" as a function subprogram, Set "cut" according to e, and find the FWHM of the B array. Suppress output with ";". Insert appropriate comments. g. Your code should print out (nicely, with fprintf): "FWHM of bacteria at time 300 sec is" FWHM_value "microns, at height" cut_value