Cell array, self-defined function, and save fig

I learned a lot of important things yesterday, after spend 10 hours in front of computer playing with MatLab. Alright, here's the code I came up with.


%Created on 6/30/2011
clear all
clc
sitenumber='01';


SampleLocation=[];
AER=[];
Err=[];




%% Importing data from intermediate file
filename='whatever it is.xlsx';
D1=xlsread(filename, 'A14:C25');
D2=xlsread(filename, 'I14:K25');
D3=xlsread(filename, 'Q14:S25');
D4=xlsread(filename, 'Y14:AA25');
D5=xlsread(filename, 'AG14:AI25');
D6=xlsread(filename, 'AO14:AQ25');
D7=xlsread(filename, 'AW14:AY25');
D8=xlsread(filename, 'BE14:BG25');
D9=xlsread(filename, 'BM14:BO25');
D10=xlsread(filename, 'BU14:BW25');
D11=xlsread(filename, 'CA14:CD25');
D12=xlsread(filename, 'CJ14:CL25');
D13=xlsread(filename, 'CR14:CT25');
D14=xlsread(filename, 'CZ14:DB25');
D15=xlsread(filename, 'DH14:DJ25');
D16=xlsread(filename, 'DP14:DR25');
D17=xlsread(filename, 'DX14:DZ25');
D18=xlsread(filename, 'EF14:EH25');
DCell={D1,D2,D3,D4,D5,D6,D7,D8,D9,D10,...
    D11,D12,D13,D14,D15,D16,D17,D18}; % Put all the arrays into one big cell array so that each time I can take one cell out and use it as the function input. 


% Use each array as function input % This is a self-defined function
for k=1:18
    [AERate Error]=getDecayrate(DCell{k}); %If use DCell (k), the function won't work.
    
    SampleLocation(1,k)=k;
    AER(1,k)=AERate;
    Err(1,k)=Error;
        
    newfilename=strcat('Site_', sitenumber, '_SampleLocation_', num2str(k),'.fig');
    saveas(gcf,newfilename) % This saveas function works pretty good. The .fig file can be edited later in MatLab.
end


 Result=[SampleLocation', AER', Err'];


%The following function calculates the first-order decay rate of the tracer gas, and returns two parameters. 

function [AER Err] = getDecayrate( location)
%UNTITLED2 Summary of this function goes here
%   Detailed explanation goes here


%AER=Data-1;
TimeS=zeros(1, length(location))';
LNC1=zeros(1, length(location))';
LNC2=zeros(1, length(location))';
for i=2 : length(location)
        TimeS(i)=(location(i,1)-location(1,1))*1440/60;
end


for j=2 : length(location)
    LNC1(j)=log(location(j,2)/location(1,2));
    LNC2(j)=log(location(j,3)/location(1,3));
end


slope1=sum(TimeS.*LNC1)/sum(TimeS.^2);
slope2=sum(TimeS.*LNC2)/sum(TimeS.^2);
AER=abs((slope1+slope2)/2);
Err=abs(AER-abs(slope1));
TimeModel=0:0.01:max(TimeS);
LNC1Model=TimeModel.*slope1;
LNC2Model=TimeModel.*slope2;
plot(TimeS, LNC1, 'xr',TimeS, LNC2, 'sb', TimeModel, LNC1Model,'r', TimeModel, LNC2Model, 'b', 'MarkerSize',10, 'LineWidth', 2)
title ('Location')
xlabel('Time (hours)')
ylabel('Ln(C/C0)')
end

simple data matching by using dataset arrays

Task : There are two Excel files, one contains the sample number and the time of sampling while the other contains the analysis results of each sample. Because the samples were taken in a chronicle order and were analysed in random order, it is kind of time consuming to manually find out each sample's result and put them into one file, especially when dealing with thousands of samples.

Here's a short code I wrote to do this:

% This program search the bag numbers and put the corresponding
% concentration values into the data file.
%% initialization
clear all;
clc;


%% import data
dataf=dataset('xlsfile','back.xls'); %aisle files from field test
concf=dataset('xlsfile','concentration.xls'); %concentration readings from autoTrac


%% determine dataset array size
datafL=length(dataf);
concfL=length(concf);


%% search and match
for i=1 : datafL
 for j= 1 : concfL-1
     
               if (  char(dataf.BagNumber(i))==char(concf.BagNumber(j))  )
                            dataf.Concentration1(i)=concf.Concentration(j);
                            dataf.Concentration2(i)=concf.Concentration(j+1);
                             break
               end
 end
end


%% Output data
export(dataf, 'xlsfile', 'Processed bag files-back.xls')

The dataset array is very power at handling different type of data, including numbers, strings, and even matrix.
To write a dataset array to an Excel file, I need to use export function instead of xlswrite.

How to insert a space in Mathtype equations

It took me a while to figure out how to insert a space in Mathtype equations. This is especially useful when you write an equation with multiplication of a few items, but you don't want to use a dot or a multiplication sign. Here is the trick:

Ctrl + Shift + space

Done!

A Tai Chi wallpaper for your desktop

I learned photoshop CS2 recently. Here is a wallpaper I made. Please feel free to download it and use it as your desktop.

solve linear equation system

To solve a linear equations system:

x+y+z=3
2x+2y+z=5
4x+8y-3z=9

linsolve is the function to use.

a=[1 1 1; 2 2 1; 4 8 -3];
b=[3;5;9];
linsolve(a,b)

Done!

roots function and solve functioin

Today I learned two methods to solve polynomial.Two functions, roots and solve can be used. For example, if I would like to solve the polynomial:

x^3+2*x^2-8*x+10=0

I can use:

r=roots([1 2 -8 10])

or:

solve('x^3+2*x^2-8*x+10')

However, the answers will be given in different form. The first one will give numerical values of the roots, like:

ans =

  -4.3605          

   1.1803 + 0.9488i

   1.1803 - 0.9488i

the latter one will give symbolic form answers:

ans =

 

-1/3*(215+3*2697^(1/2))^(1/3)-28/3/(215+3*2697^(1/2))^(1/3)-2/3

 1/6*(215+3*2697^(1/2))^(1/3)+14/3/(215+3*2697^(1/2))^(1/3)-2/3+1/2*i*3^(1/2)*(-1/3*(215+3*2697^(1/2))^(1/3)+28/3/(215+3*2697^(1/2))^(1/3))

 1/6*(215+3*2697^(1/2))^(1/3)+14/3/(215+3*2697^(1/2))^(1/3)-2/3-1/2*i*3^(1/2)*(-1/3*(215+3*2697^(1/2))^(1/3)+28/3/(215+3*2697^(1/2))^(1/3))

 

 

I was using a lot of greek symbols in my Word document, and usually when I need one, I input a English letter, for example, "a", then highlight it and change the font to symbol. That way, I will have a "α" there. However, if someone changed the font of that letter, it won't show up correctly- a blank will be left there instead of the letter you want.

I did some research and found one way to solve this problem: Firstly type in the unicode for the greek letter, then press "Alt+X". The unicode will be turned into a greek letter, and changing the font will not cause any trouble. The greek letter will show up anyway, just look a little different when different font is used.

And here is the reference for the unicode. This is very cool!

0391 Α  GREEK CAPITAL LETTER ALPHA

0392 Β  GREEK CAPITAL LETTER BETA

0393 Γ  GREEK CAPITAL LETTER GAMMA

0394 Δ  GREEK CAPITAL LETTER DELTA

0395 Ε  GREEK CAPITAL LETTER EPSILON

0396 Ζ  GREEK CAPITAL LETTER ZETA

0397 Η  GREEK CAPITAL LETTER ETA

0398 Θ  GREEK CAPITAL LETTER THETA

0399 Ι  GREEK CAPITAL LETTER IOTA

039A Κ  GREEK CAPITAL LETTER KAPPA

039B Λ  GREEK CAPITAL LETTER LAMDA

039C Μ  GREEK CAPITAL LETTER MU

039D Ν  GREEK CAPITAL LETTER NU

039E Ξ  GREEK CAPITAL LETTER XI

039F Ο  GREEK CAPITAL LETTER OMICRON

03A0 Π  GREEK CAPITAL LETTER PI

03A1 Ρ  GREEK CAPITAL LETTER RHO

03A3 Σ  GREEK CAPITAL LETTER SIGMA

03A4 Τ  GREEK CAPITAL LETTER TAU

03A5 Υ  GREEK CAPITAL LETTER UPSILON

03A6 Φ  GREEK CAPITAL LETTER PHI

03A7 Χ  GREEK CAPITAL LETTER CHI

03A8 Ψ  GREEK CAPITAL LETTER PSI

03A9 Ω  GREEK CAPITAL LETTER OMEGA

03AA Ϊ  GREEK CAPITAL LETTER IOTA WITH DIALYTIKA

03AB Ϋ  GREEK CAPITAL LETTER UPSILON WITH DIALYTIKA

03B1 α  GREEK SMALL LETTER ALPHA

03B2 β  GREEK SMALL LETTER BETA

03B3 γ  GREEK SMALL LETTER GAMMA

03B4 δ  GREEK SMALL LETTER DELTA

03B5 ε  GREEK SMALL LETTER EPSILON

03B6 ζ  GREEK SMALL LETTER ZETA

03B7 η  GREEK SMALL LETTER ETA

03B8 θ  GREEK SMALL LETTER THETA

03B9 ι  GREEK SMALL LETTER IOTA

03BA κ  GREEK SMALL LETTER KAPPA

03BB λ  GREEK SMALL LETTER LAMDA

03BC μ  GREEK SMALL LETTER MU

03BD ν  GREEK SMALL LETTER NU

03BE ξ  GREEK SMALL LETTER XI

03BF ο  GREEK SMALL LETTER OMICRON

03C0 π  GREEK SMALL LETTER PI

03C1 ρ  GREEK SMALL LETTER RHO

03C2 ς  GREEK SMALL LETTER FINAL SIGMA

03C3 σ  GREEK SMALL LETTER SIGMA

03C4 τ  GREEK SMALL LETTER TAU

03C5 υ  GREEK SMALL LETTER UPSILON

03C6 φ  GREEK SMALL LETTER PHI

03C7 χ  GREEK SMALL LETTER CHI

03C8 ψ  GREEK SMALL LETTER PSI

03C9 ω  GREEK SMALL LETTER OMEGA

03D1 ϑ  GREEK THETA SYMBOL

03D2 ϒ  GREEK UPSILON WITH HOOK SYMBOL

03D5 ϕ  GREEK PHI SYMBOL

03D6 ϖ  GREEK PI SYMBOL

03DC Ϝ   GREEK LETTER DIGAMMA

03F0 ϰ  GREEK KAPPA SYMBOL

03F1 ϱ   GREEK RHO SYMBOL