Графики в логарифмическом масштабе

 

 

» x=logspace(-1,3);

» loglog(x.*exp(x)./x)

» grid on

 

semilogx(...) — строит график функции в логарифмическом масштабе (основание 10) по оси X и линейном по оси Y; semilogy (...) — строит график функции в логарифмическом масштабе по оси Y и линейном по оси X.

 

» х=0:0.5:10;

» semilogy(x.exp(x))

>> grid on

 

 

Построение гистограмм

>> x=-3:0.2:3;

>> y=randn(1000,1);

>> hist(y,x)

>> help randn

 

RANDN Normally distributed random numbers.

RANDN(N) is an N-by-N matrix with random entries, chosen from a normal distribution with mean zero, variance one and standard deviation one.

RANDN(M,N) and RANDN([M,N]) are M-by-N matrices with random entries. RANDN(M,N,P,...) or RANDN([M,N,P...]) generate random arrays. RANDN with no arguments is a scalar whose value changes each time it is referenced. RANDN(SIZE(A)) is the same size as A.

 

RANDN produces pseudo-random numbers. The sequence of numbers generated is determined by the state of the generator. Since MATLAB resets the state at start-up, the sequence of numbers generated will be the same unless the state is changed.

 

S = RANDN('state') is a 2-element vector containing the current state of the normal generator. RANDN('state',S) resets the state to S. RANDN('state',0) resets the generator to its initial state. RANDN('state',J), for integer J, resets the generator to its J-th state.

RANDN('state',sum(100*clock)) resets it to a different state each time.

MATLAB Version 4.x used random number generators with a single seed. RANDN('seed',0) and RANDN('seed',J) cause the MATLAB 4 generator to be used. RANDN('seed') returns the current seed of the MATLAB 4 normal generator. RANDN('state',J) and RANDN('state',S) cause the MATLAB 5 generator to be used.

 

See also RAND, SPRAND, SPRANDN, RANDPERM.

 

 

 

 

Bar plot of a bell shaped curve

x = -2.9:0.2:2.9;

bar(x,exp(-x.*x));

 

 

Stairstep plot of a sine wave

x=0:0.25:10;

stairs(x,sin(x));

 

 

Errorbar plot

x=-2:0.1:2;

y=erf(x);

e = rand(size(x))/10;

errorbar(x,y,e);

 

 

 

Polar plot

t=0:.01:2*pi;

polar(t,abs(sin(2*t).*cos(2*t)));

Stem plot

x = 0:0.1:4;

y = sin(x.^2).*exp(-x);

stem(x,y)

 

 

XYZ plots in MATLAB.

 

 

D Surface Plots

>> graf3d

Demonstrate Handle Graphics for surface plots in MATLAB. This window allows you to assemble a string of MATLAB commands that results in a plot in

the axis in the upper left corner.

 

By playing with the popup menus on the right side of the window, you can adjust the type of plot, the type of shading, the color map,

and so on.

The MiniCommand Window in the lower

right shows the list of commands that create

the plot. If you like, you can even directly edit

the commands in the MiniCommand Window.

Type control-return to execute code in the

MiniCommand Window.

Line Plotting

>> hndlgraf

Demonstrates Handle Graphics for line plots in MATLAB. This window allows you to assemble a string of MATLAB commands that results in a plot in

the axis in the upper left corner.

By playing with the popup menus on the right side of the window, you can adjust the line style of the plot, the line width, the marker size, and the color using Handle Graphics.

 

The MiniCommand Window in the lower right shows the list of commands that create the plot. If you like, you can even directly edit the commands in the MiniCommand Window. Type control-return to execute code in the

MiniCommand Window.

 

Axes Properties

>> hndlaxis

Demonstrates Handle Graphics for axes in MATLAB.

This window allows you to assemble a string

of MATLAB commands that results in a plot in

the axis in the upper left corner.

 

By playing with the popup menus on the right

side of the window, you can adjust the scaling

for the axes, the grid lines, the direction of the

plot and the color of the axes using Handle

Graphics.

 

The MiniCommand Window in the lower

right shows the list of commands that create

the plot. If you like, you can even directly edit

the commands in the MiniCommand Window.

Type control-return to execute code in the

MiniCommand Window.

 

P = round(poly(A)) % The characteristic polynomial of a matrix

P =

1 -5 5 -1

 

R = roots(P) % Roots of a polynomial

R =

3.7321

1.0000

0.2679

Q = conv(P,P) % Convolve two vectors

R = conv(P,Q)

Q = 1 -10 35 -52 35 -10 1

R = 1 -15 90 -278 480 -480 278 -90 15 -1

stem(R); % Plot the result