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LAB 1 General MATLAB Information
General:
To enter a matrix:
> type the entries between square brackets, [.....]
> enter it by rows with elements separated by a space or comma
> rows are terminated by a semicolon
command A= [1 2 3;4 5 6;7 8 9] displays
Suppressing Displays: When you place a semicolon at
the end of a command, the
command will be executed but the result will not be displayed on the screen.
This is
very useful when you are creating big matrices or to not reveal intermediate
steps of
a calculation . Try typing the command
w = linspace(1,20,100); Note the semicolon
to create a row vector with equally spaced entries. The contents of w will not
be
displayed. To see the contents just type w.
To enter a string: type the contents of the string between single quotes
' ... '
command st = 'Hi there.'
displays
st =
Hi
there.
Strings are not commands.
Strings supply information.
Strings are used for messages and formulas.
What you see on the screen: MATLAB has various display formats. That
is, ways to
show things on the screen. All numerical values stored by MATLAB have about 16
decimal places . However, we do not always want to see all the decimals places.
That is
why MATLAB has display formats.
The default format is format short.
Format short shows 4 places behind the decimal point for reasonable sized
numbers.
Examples:
pi is shown as 3.1416 in format short
2/3 is shown as 0.6667 in format short
1/8 is shown as 0.1250 in format short
(Format short rounds to obtain the last digit which is displayed. Beware,
there may be
many more decimal places than those shown.)
Examples of other display formats: (e formats or
floating point formats display a
number and an exponent which is a power of ten ; 1.2345e+002 means 1.2345*10^{2} )
FORMAT SHORT Scaled fixed point format with 5 digits.
FORMAT LONG Scaled fixed point format with 15 digits.
FORMAT SHORT E Floating point format with 5 digits.
FORMAT LONG E Floating point format with 15 digits.
FORMAT SHORT G Best of fixed or floating point format with 5 digits.
FORMAT LONG G Best of fixed or floating point format with 15 digits.
FORMAT RAT Approximation by ratio of small integers.
format short e shows pi as
3.1416e+000
format long shows pi as
3.14159265358979
format long e shows pi as
3.141592653589793e+000
format rat shows pi as
355/113
Note: 355/113 is only an approximation to pi; computing 355/113 in format long
gives
3.14159292035398
Use command help format for the description of other display formats.
Special case: A value which is exactly zero will
be displayed as a single zero. If you see 0.0000, the value is not exactly zero. Change to a long format and redisplay it. 
Illustrations of ALGEBRA Expressions and their MATLAB form.
Standard Algebra Form  MATLAB Representation 
3x^{2}  5x + 1  3*x^25*x+1 multiplication must be indicated using * and exponents require an ^ 
(2*x3)/(47*x) the numerator and denominator must be enclosed in parentheses if they are more than 1 term 

sqrt(x^2+1) or (x^2+1)^.5 or (x^2+1)^(1/2) using sqrt is preferred ; fractional exponents must be enclosed in parentheses 

exp(x)  
ln(x)  log(x) the natural log function is denoted log; log base 10 is denoted log10 
cos^{2}(x  π)  cos(xpi)^2 constant π is denoted pi; all arguments of trig. functions are considered radians 
sin(x) e^{2.3x}  sin(x)*exp(2.3*x) note that the exponent is in parentheses and that we must use * to indicate multiplication 
tan(x)  abs(tan(x)) the absolute value is denoted by abs; parentheses must be used 
Operators, Elementary Functions, & General Purpose Commands
Arithmetic operators .  
plus minus times power divide 
+  * ^ \ 
Relational operators.  
Equal Not equal Less than Greater than Less than or equal Greater than or equal 
== ~= < > <= >= 
Logical operators.  
and or not 
&  ~ 
Trigonometric & Hyperbolic  
sin   Sine. 
sinh   Hyperbolic sine. 
asin   Inverse sine. 
asinh   Inverse hyperbolic sine. 
cos   Cosine. 
cosh   Hyperbolic cosine. 
acos   Inverse cosine. 
acosh   Inverse hyperbolic cosine. 
tan   Tangent. 
tanh   Hyperbolic tangent. 
atan   Inverse tangent. 
atan2 
 Four quadrant inverse tangent. 
atanh   Inverse hyperbolic tangent. 
sec   Secant. 
sech   Hyperbolic secant. 
asec   Inverse secant. 
asech   Inverse hyperbolic secant. 
csc   Cosecant. 
csch   Hyperbolic cosecant. 
acsc   Inverse cosecant. 
acsch   Inverse hyperbolic cosecant. 
cot   Cotangent. 
coth   Hyperbolic cotangent. 
acot   Inverse cotangent. 
acoth   Inverse hyperbolic cotangent. 
Exponential  
exp   Exponential. 
log   Natural logarithm. 
log10   Common (base 10) logarithm. 
log2 
 Base 2 logarithm and dissect floating point number. 
pow2 
 Base 2 power and scale floating point number. 
sqrt   Square root . 
nextpow2   Next higher power of 2. Complex 
Complex  
abs   Absolute value. 
angle   Phase angle. 
complex 
 Construct complex data from real and imaginary parts. 
conj   Complex conjugate. 
imag   Complex imaginary part. 
real   Complex real part. 
Calculus Operators  
diff 
 Difference and approximate derivative when working on a vector. 
diff

 Differentiate when working on a string or symbolic expression ; will do higher derivatives & partial derivatives 
int 
Integrate; indefinite or definite depending upon the arguments. 
General Purpose Commands  
home

Moves the cursor to the upper left corner of the Command Window and clears the visible portion of the window. You can use the scroll bar to see what was on the screen previously. 
clc   Clear command window; scrollbar not available. 
demo   Run demonstrations. 
who   List current variables. 
whos   List current variables, long form. 
clear   Clear variables and functions from memory. 
load   Load workspace variables from disk. 
save   Save workspace variables to disk. 
saveas   Save Figure or model to desired output format. 
quit   Quit MATLAB session. 
exit   Exit from MATLAB. 
what   List MATLABspecific files in directory. 
type   List Mfile. 
which   Locate functions and files. 
path   Get/set search path. 
addpath   Add directory to search path. 
rmpath   Remove directory from search path. 
diary   Save text of MATLAB session. 
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