Appendix: MATLAB® characters, operators and commands – Matlab® in Bioscience and Biotechnology

Appendix: MATLAB® characters, operators and commands

Characters, arithmetic, rational and logical operators

Character, operator Description Page(s)
+ Addition 6, 19
Subtraction 6
* Scalar and matrix multiplication 6, 20
.* Element-wise multiplication 28
/ Right division 6, 26
\ Left division 6, 26
./ Element-wise right division 28
.\ Element-wise left division 28
^ Exponentiation 6
.^ Element-wise exponentiation 28
= Assignment 6
% Percent; use for comments and for output format specification 6, 11
() Parentheses; use for input arguments and in matrix addressing 6, 15, 18
[] Brackets; use for vector, matrix, array elements input 15, 17
(space) Space; separates elements into arrays, and adds into output specifications 15, 18
, Comma; separates elements into arrays, and commands on the same line 6, 15
: Semicolon 6
Ellipsis 6
< Less than 34
> Greater than 34
<= Less than or equal to 34
>= Greater than or equal to 34
= = Equal 34
~= Not equal 34
& Logical AND 35
| Logical OR 35
~ Logical NOT 35

Help and managing commands

Command Description Page
clear Remove variables from the Workspace 10
clc Clear the Command Window 6
close Closes one or more Figure Windows 53
help Displays explanations for commands 7
help graph2d Displays list of 2D graphs 76
help graph3d Displays list of 3D graphs 76
help specgraph Displays list of specialized graph commands 76
doc Displays HTML documentation in the Help window 9
function Creates a new function 100
global Declares a global variable 102
lookfor Search for the word in all help entries 9
ver Displays versions of the MATLAB® products 171
who Displays variables stored in the Workspace 10
whos Displays Workspace variables and additional information about the variables 10

Predefined variables and elementary math functions

Variable, Function Description Page
abs Absolute value 7
ans Last calculated or defined value 8
exp Exponential 7
factorial Factorial function 7
floor Round off toward minus infinity 7
i √–1 10
inf Infinity 10
j The same as i 10
log Natural logarithm 7
log10 Decimal logarithm 7
NaN Not a number 10
pi Number π 7
round Round off toward nearest integer 7
sqrt Square root 7
sin Sine 7
cos Cosine 7
tan Tangent 7
cot Cotangent 7
asin Inverse sine 7
acos Inverse cosine 7
atan Inverse tangent 7
acot Inverse cotangent 7

Relational and logical commands

Character, command Description Page
and Logical AND 35
or Logical OR 35
not Logical NOT 35
find Finds indices of certain elements of array 35

Flow control commands

Command Description Page(s)
else Is used with if 37
elseif conditionally execute if statement condition 37
end Terminates scope of for, while, if statements, or serves as last index 17, 37
for Repeat execution of command/s 37
if Conditionally execute 37
while Repeat execution of command/s 38

Array, matrix, and vector commands

Command Description Page(s)
colon (:) Is used for creating a vector 15
det Calculates a determinant 27
diag Creates a diagonal matrix from a vector 26
eye Creates a unit matrix 22, 26
inv Calculates the inverse matrix 22
length Number of elements in vector 26
reshape Changes size of a matrix 26
linspace Generates a linearly spaced vector 16
max Returns maximal value 27
min Returns minimal value 27
mean Calculates mean value 27
ones Creates an array with ones 25
rand Generates an array with uniformly distributed random numbers 25
randi Generates an array with integer random numbers from uniform discrete distribution 25, 27
randn Generates an array with normally distributed numbers 25
size Size of array/matrix 26
sort Arranges elements in ascending or descending order 27
std Calculates standard deviation 27
strvcat Concatenates strings vertically 26
sum Calculates sum of elements 27
Transpose (') Transposes elements of an array 19
zeros Creates an array with zeros 25

Input, output, display format, and convert commands

Command Description Page
disp Displays output 11
fprintf Displays or saves formatted output 11
input Prompts to user input 99
format Sets current output format 8
num2str Converts numbers to a string 27

Two- and three-dimensional plotting and plot formatting

Command Description Page
axis Controls axis scaling and appearance 57
bar Generates vertical bars on the plot 78
bar3 Generates 3D vertical bars on the plot 78
box, box on/off Adds a box to the current axes, keeps/ removes a box on the axes 68
clabel Labels iso-level lines 78
colormap Sets colors 68
contour Creates a 2D-contour plot 78
contour3 Creates a 3D-contour plot 78
cylinder Generates a cylinder 77
errorbar Creates a plot with error-bounded points 73
figure Creates the Figure window 77
fplot Creates a 2D plot of a function 77
gtext Adds text with the help of the mouse 59
grid Adds grid lines 57
hist Plots a histogram 73
hold on, hold of Keeps current graph open, ends hold on 53
legend Adds a legend to the plot 59
loglog Generates a 2D plot with log axes 77
mesh Creates a 3D plot with meshed surface 66
meshgrid Creates X,Y matrices for further plotting 65
pie Creates a 2D pie plot 79
pie3 Creates a 3D pie plot 79
plot Creates a 2D plot 53
plot3 Creates a 3D plot with points and/or lines 63
polar Creates a 2D plot in polar coordinates 77
polyfit Fits the data by a polynomial 114
polyval Evaluates the polynomial value 114
rotate3d Interactively rotates a 3D plot 72
semilogx Creates a 2D plot with log-scaled x-axis 75
semilogy Creates a 2D plot with log-scaled y-axis 75
sphere Generates a sphere plot 77
stem Creates a 2D stem plot 79
subplot Places multiple plots on the same page 55
surf Creates a 3D surface plot 66
surfc Generates surface and counter plots together 78
text Adds text to the plot 59
title Adds a caption to the plot 59
view Specifies a viewpoint for 3D graph 70
xlabel Adds a label to x-axis 59
ylabel Adds a label to y-axis 59
zlabel Adds a label to z-axis 63

Math functions, integration and differentiation

Command Description Page
diff Calculates a difference, approximates a derivative 110
fzero Solves a one-variable equation 107
interpl One-dimensional interpolation 105
quad Numerical integration with Simpson’s rule 108
trapz Numerical integration with the trapezoidal rule 109

Ordinary and partial equation solvers

Command Description Page
ode15s Solves stiff ODEs 135
ode15i Solves implicit ODEs 135
ode23 Solves non-stiff ODEs 135
ode23s Solves stiff ODEs 135
ode23t Solves stiff ODEs 135
ode23tb Solves stiff ODEs 135
ode45 Solves non-stiff ODEs 135
odell3 Solves non-stiff ODEs 135
odeset Sets ODE options 170
pdepe Solves 1D parabolic and elliptic PDEs 153

Bank access and sequence analysis

Command Description Page
aa2nt Converts a sequence of amino acids to a nucleotide sequence 183
aacount Counts amino acids in a sequence 184
aminolookup Finds amino acid or codon codes 188
basecount Counts nucleotides in sequence 188
baselookup Returns nucleotide codes 188
blastncbi Requests NCBI BLAST report and its ID 181
codoncount Calculates codons in nucleotide sequence 189
dimercount Calculates dimers in nucleotide sequence 189
emblread Reads data stored in EMBL-formatted file 181
genbankread Reads data stored in GenBank-formatted file 178
genpeptread Reads data stored in GenPept-formatted file 180
getblast Gets BLAST report generated in NCBI website 182
getgenbank Gets data from GenBank database 178
getgenpept Gets sequence info from GenPept database 179
getgeodata Gets data in GEO format 180
getembl Gets sequence info from EMBL database 179
getpdb Gets protein 3D data from PDB database 180
molviewer Generates 3D molecule image 181
molweight Calculates molecular weight of amino acids 189
multialign Aligns multiple sequences 194
multialignviewer Displays and interactively adjusts multiple sequence alignment 197
nt2aa Converts nucleotide to amino acid sequence 206
ntdensity Plots nucleotide densities along sequence 186
nwalign Aligns two sequences globally 192
pdbread Reads data stored in PDB-formatted file 181
randseq Generates letter-coded random sequence 183
seqdotplot Generates dot plot for two sequences 194
seqshoworfs Shows open reading frames 184
showalignment Displays results of alignment 196
swalign Aligns two sequences locally 209
web Opens website or file in Web Browser window 175