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Matlab

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anandengg's version from 2018-05-19 08:33

Section

Question Answer
exist Checks for existence of file or variable.
global Declares variables to be global.
lookfor Searches help entries for a keyword.
quit Stops MATLAB.
who Lists current variables.
whos Lists current variables (long display).
cd Changes current directory.
date Displays current date.
delete Deletes a file.
diary Switches on/off diary file recording.
dir Lists all files in current directory.
load Loads workspace variables from a file.
path Displays search path.
pwd Displays current directory.
save Saves workspace variables in a file.
type Displays contents of a file.
what Lists all MATLAB files in the current directory.
wklread Reads .wk1 spreadsheet file.
memorize

 

Question Answer
\n Insert a new line in the output string.
\t Insert a tab in the output string.
format short Four decimal digits (default).
format long 16 decimal digits.
format short e Five digits plus exponent.
format long e 16 digits plus exponents.
format bank Two decimal digits.
format + Positive, negative, or zero.
format rat Rational approximation.
format compact Suppresses some line feeds.
format loose Resets to less compact display mode.
memorize

 

Question Answer
cat Concatenates arrays.
find Finds indices of nonzero elements.
length Computes number of elements.
linspace Creates regularly spaced vector.
logspace Creates logarithmically spaced vector.
max Returns largest element.
min Returns smallest element.
memorize

 

Question Answer
prod Product of each column.
reshape Changes size.
size Computes array size.
sort Sorts each column.
sum Sums each column.
eye Creates an identity matrix.
ones Creates an array of ones.
zeros Creates an array of zeros.
cross Computes matrix cross products.
dot Computes matrix dot products.
det Computes determinant of an array.
inv Computes inverse of a matrix.
pinv Computes pseudoinverse of a matrix.
rank Computes rank of a matrix.
rref Computes reduced row echelon form.
cell Creates cell array.
celldisp Displays cell array.
cellplot Displays graphical representation of cell array.J
num2cell Converts numeric array to cell array.
deal Matches input and output lists.
iscell Identifies cell array.
memorize

 

Question Answer
axis Sets axis limits.
fplot Intelligent plotting of functions.
grid Displays gridlines.
plot Generates xy plot.
print Prints plot or saves plot to a file.
title Puts text at top of plot.
xlabel Adds text label to x-axis.
ylabel Adds text label to y-axis.
axes Creates axes objects.
close Closes the current plot.
close all Closes all plots.
figure Opens a new figure window.
gtext Enables label placement by mouse.
hold Freezes current plot.
legend Legend placement by mouse.
refresh Redraws current figure window.
set Specifies properties of objects such as axes.
subplot Creates plots in subwindows.
text Places string in figure.
bar Creates bar chart.
loglog Creates log-log plot.
polar Creates polar plot.
semilogx Creates semilog plot. (logarithmic abscissa).
semilogy Creates semilog plot. (logarithmic ordinate).
stairs Creates stairs plot.
stem Creates stem plot.
memorize

clear Removes variables from memory.

 

exist Checks for existence of file or variable.
global Declares variables to be global.
help Searches for a help topic.
lookfor Searches help entries for a keyword.
quit Stops MATLAB.
who Lists current variables.
whos Lists current variables (long display).

Special Variables and Constants

 

ans Most recent answer.
eps Accuracy of floating-point precision.
i,j The imaginary unit -1.
Inf Infinity.
NaN Undefined numerical result (not a number).
pi The number p .
System and File Commands
cd Changes current directory.
date Displays current date.
delete Deletes a file.
diary Switches on/off diary file recording.
dir Lists all files in current directory.
load Loads workspace variables from a file.
path Displays search path.
pwd Displays current directory.
save Saves workspace variables in a file.
type Displays contents of a file.
what Lists all MATLAB files in the current directory.
wklread Reads .wk1 spreadsheet file.

Input/Output and Formatting Commands

 

Input/Output Commands
disp Displays contents of an array or string.
fscanf Read formatted data from a file.
format Controls screen-display format.
fprintf Performs formatted writes to screen or file.
input Displays prompts and waits for input.
; Suppresses screen printing.

Vector, Matrix and Array Commands

cat Concatenates arrays.
find Finds indices of nonzero elements.
length Computers number of elements.
linspace Creates regularly spaced vector.
logspace Creates logarithmically spaced vector.
max Returns largest element.
min Returns smallest element.
prod Product of each column.
reshape Change size
size Computes array size.
sort Sorts each column.
sum Sums each column.
Special Matrices
eye Creates an identity matrix.
ones Creates an array of ones.
zeros Creates an array of zeros.
Matrix Arithmetic
cross Computes cross products.
dot Computes dot products.
Matrix Commands for Solving Linear Equations
det Computes determinant of an array.
inv Computes inverse of a matrix.
pinv Computes pseudoinverse of a matrix.
rank Computes rank of a matrix.
rref Computes reduced row echelon form.

Cell Array Functions

cell Creates cell array.
celldisp Displays cell array.
cellplot Displays graphical representation of cell array.
Question Answer
num2cell Converts numeric array to cell array.
deal Matches input and output lists.
memorize
iscell Identifies cell array.
Question Answer
Structure Functions
fieldnames Returns field names in a structure array.
getfield Returns field contents of a structure array.
isfield Identifies a structure array field.
isstruct Identifies a structure array.
rmfield Removes a field from a structure array.
setfield Sets contents of field.
struct Creates structure array.
memorize

Plotting Commands

 

Basic xy Plotting Commands
axis Sets axis limits.
fplot Intelligent plotting of functions.
grid Displays gridlines.
plot Generates xy plot.
print Prints plot or saves plot to a file
title Puts text at top of plot.
xlabel Adds text label to x-axis.
ylabel Adds text label to y-axis.
Plot Enhancement Commands
axes Creates axes objects.
close Closes the current plot.
close all Closes all plots.
figure Opens a new figure window.
gtext Enables label placement by mouse.
hold Freezes current plot.
legend Legend placement by mouse.
refresh Redraws current figure window.
set Specifies properties of objects such as axes.
subplot Creates plots in subwindows.
text Places string in figure.
Specialized Plot Commands
bar Creates bar chart.
loglog Creates log-log plot.
polar Creates polar plot.
semilogx Creates semilog plot (logarithmic abscissa).
semilogy Creates semilog plot (logarithmic ordinate).
stairs Creates stairs pot.
stem Creates stem plot.

Three-Dimensional Plotting Commands

 

contour Creates contour plot.
mesh Creates three-dimensional mesh surface plot.
meshc Same as mesh with contour plot underneath.
meshz Same as mesh with vertical lines underneath.
plot3 Creates three-dimensional plots from lines and points.
surf Creates shaded three-dimensional mesh surface plot.
surfc Same as surf with contour plot underneath.
meshgrid Creates rectangular grid.
waterfall Same as mesh with mesh lines in one direction.
zlabel Adds text label to z-axis.
Histogram Functions
bar Creates a bar chart.
hist Aggregates the data into equally spaced bins.
histc Aggregates the data into unequally spaced bins.

Programming Logical and Relational Operators

Relational operator : equal to.

Question Answer
~= Relational operatornot equal to.
< Relational operatorless than.
<= Relational operatorless than or equal to.
> Relational operatorgreater than.
memorize
>= Relational operator: greater than or equal to.
& Logical operator: AND.
| Logical operator: OR.
~ Logical operator: NOT.
xor Logical operator: EXCLUSIVE OR.
Program Flow Control
break Terminates execution of a loop.
case Provides alternate execution paths within switch structure.
else Delineates alternate block of statements.
elseif Conditionally executes statements.
end Terminates for, while, and if statements.
error Display error messages.
for Repeats statements a specific number of times
if Executes statements conditionally.
otherwise Default part of switch statement.
return Return to the invoking function.
switch Directs program execution by comparing point with case expressions.
warning Display a warning message.
while Repeats statements an indefinite number of times.

Logical Functions

 

any True if any elements are nonzero.
all True if all elements are nonzero.
find Finds indices of nonzero elements.
finite True if elements are finite.
isnan True if elements are undefined.
isinf True if elements are infinite.
isempty True if matrix is empty.
isreal True if all elements are real.

 

eval Interpret strings containing Matlab expressions.
feval Function evaluation.
function Creates a user-defined function M-file.
global Define global variables.
nargin Number of function input arguments.
nargout Number of function output arguments.
script Script M-files
Timing
cputime CPU time in seconds.
clock Current date and time as date vector.
tic, toc Start, stop a stopwatch timer.

Mathematical Functions Exponential and Logarithmic Functions

 

exp(x) Exponential; ex.
log(x) Natural logarithm; ln(x).
log10(x) Common (base 10) logarithm; log(x)= log10(x).
sqrt(x) Square root; x.

 

Hyperbolic Functions

 

Question Answer
acosh(x) Inverse hyperbolic cosine; cosh –1 (x).
acoth(x) Inverse hyperbolic cotangent; coth –1 (x).
acsch(x) Inverse hyperbolic cosecant; csch –1 (x).
asech(x) Inverse hyperbolic secant; sech –1 (x).
asinh(x) Inverse hyperbolic sine; sinh –1 (x).
atanh(x) Inverse hyperbolic tangent; tanh –1 (x).
cosh(x) Hyperbolic cosine; cosh(x).
coth(x) Hyperbolic cotangent; cosh(x)/sinh(x).
csch(x) Hyperbolic cosecant; 1/sinh(x).
sech(x) Hyperbolic secant; 1/cosh(x).
sinh(x) Hyperbolic sine; sinh(x).
tanh(x) Hyperbolic tangent; sinh(x)/cosh(x).
memorize

 

Complex Functions

 

Question Answer
abs(x) Absolute value; |x|.
angle(x) Angle of a complex number x.
conj(x) Complex conjugate of x.
imag(x) Imaginary part of a complex number x.
real(x) Real part of a complex number x.
memorize

 

Statistical Functions

 

Question Answer
erf(x) Computes the error function erf (x).
mean Calculates the average.
median Calculates the median.
std Calculates the standard deviation.
memorize

 

Random Number Functions

 

Question Answer
rand Generates uniformly distributed random numbers between 0 and 1.
randn Generates normally distributed random numbers.
memorize

 

Numeric Functions

 

Question Answer
ceil Rounds to the nearest integer toward •.
fix Rounds to the nearest integer toward zero.
floor Rounds to the nearest integer toward - •.
round Rounds towards the nearest integer.
sign Signum function.
memorize

String Functions

Question Answer
findstr Finds occurrences of a string.
strcmp Compares strings.
char Creates character string array
memorize

Polynomial and Regression Functions

Question Answer
conv Computes product of two polynomials
deconv Computes ratio of polynomials.
eig Computes the eigenvalues of a matrix.
poly Computes polynomial from roots.
polyfit Fits a polynomial to data.
polyval Evaluates polynomial and generates error estimates.
roots Computes polynomial roots.
memorize

 

Interpolation Functions

 

Question Answer
interp1 Linear and cubic-spline interpolations of a function of one variable.
interp2 Linear interpolation of a function of two variables.
spline Cubic-spline interpolation.
unmkpp Computes the coefficients of cubic-spine polynomials.
Root Finding and Minimization
fmin Finds minimum of single-variable function.
fmins Finds minimum of multivariable function.
fzero Finds zero of single-variable function.
memorize

 

Numerical Integration Functions
Question Answer
quad Numerical integration with adaptive Simpson’s rule.
quadl Numerical integration with adaptive Lobatto quadrature.
trapz Numerical integration with the trapezoidal rule.
diff(x) Computes the difference between adjacent elements in the vector x.
polyder Differentiates a polynomial, a polynomial product, or a polynomial quotient.
memorize

 

ODE Solvers

 

Question Answer
ode23 Nonstiff, low-order solver.
ode45 Nonstiff, medium-order solver.
ode113 Nonstiff, variable-order solver.
ode23s Stiff, low-order.
ode23t Moderately stiff, trapezoidal rule solver.
ode23b Stiff, low-order solver.
ode15s Stiff, variable-order solver.
odeset Creates integrator options structure for ODE solvers.
Predefined Input Functions
gensig Generates a periodic sine, square, or pulse input.
sawtooth Generates a periodic sawtooth input.
square Generates a square wave input.
stepfun Generates a step function input.
memorize

 

Functions for Creating and Evaluating Symbolic Expressions

 

Question Answer
class Returns the class of an expression.
digits Sets the number of decimal digits used to do variable precision arithmetic.
double Converts an expression to numeric form.
ezplot Generates a plot of a symbolic expression.
findsym Finds the symbolic variables in a symbolic expression.
numden Returns the numerator and denominator of an expression.
sym Creates a symbolic variable.
syms Creates one or more symbolic variables.
vpa Sets the number of digits used to evaluate expressions.
memorize

 

Functions for Manipulating Symbolic Expressions

 

Question Answer
collect Collects coefficients of like powers in an expression.
expand Expands an expression by carrying out jpowers.
factor Factors an expression.
poly2sym Converts a polynomial coefficient vector to a symbolic polynomial.
pretty Displays an expression in a form that resembles typeset mathematics.
simple Searches for the shortest form of an expression.
simplify Simplifies an expression using Maple’s simplification rules.
subs Substitutes variables or expressions.
sym2poly Converts an expression to a polynomial coefficient vector.
memorize

 

Symbolic Calculus Functions

 

Question Answer
diff Returns the derivative of an expression.
Dirac Dirac delta function (unit impulse).
Heaviside Heaviside function (unit step).
int Returns the integral of an expression.
limit Returns the limit of an expression.
symsum Returns the symbolic summation of an expression.
taylor Returns the Taylor series of a function.
memorize

 

Symbolic Solution of Algebraic and Transcendental Equations

 

Question Answer
solve Solves symbolic equations.
Symbolic Solution of Differential Equations
dsolve Returns a symbolic solution of a differential equation or set of equations.
Laplace Transform Functions
ilaplace Returns the inverse Laplace transform.
laplace Returns the Laplace transform.
Symbolic Linear Algebra Functions
det Returns the determinant of a matrix.
eig Returns the eigenvalues (characteristic roots) of a matrix.
inv Returns the inverse of a matrix.
poly Returns the characteristic polynomial of a matrix.
memorize