MATLAB Lecture 8 Graphics Curve
绘图
Ref: MATLAB →Graphics →Basic Plotting Commands
日语学习l Vocabulary:
plot 绘图 xaxis x 轴
display 显示 annotate 注释
wrapupcurve/curved line 曲线 explicit 显式
implicit 隐式 parameter 参数
polar coordinates 极坐标 boldface 黑体
grid 网格 title 标题
figure 图形 legend 图例
radian 弧度 radius 半径
l Some functions
plot ezplot polar plot3 title xlabel ylabel *figure *legend *subplot
*grid on *grid off
l Graphics礼物英语
MA TLAB provides a variety of functions for displaying vector data as line plots, as well as functions for annotating and printing the graphs.
² The reprentation of curve and surface
ü The reprentation of curve on plane
Explicit scheme: y = f(x)
Implicit formula: F(x,y) = 0
Parameter reprentation: ()
()
x x t y y t = ì í = î Polar coordinates reprentation: ()
f r q = Tabulation, say table of trigonometric function, experimental data etc.
Figure, say sine curve, experimental curve etc.
ü The reprentation of curve in space
Explicit scheme: z = f(x,y)
Implicit formula: F(x,y,z) = 0
Parameter reprentation: (,) (,)
(,) x x u v y y u v z z u v = ì ï = í ï = î
Data form, {},{},{},1,2,...,,1,2,..., i j ij x x y y z z i m j n ===== .
Graphics
² Basic Plotting Commands
ü Plotting Steps
The process of constructing a basic graph to meet your prentation graphics requirements is outlined in the following table. The table shows ven typical steps and some example code for each.
If you are performing analysis only, you may want to view various graphs just to explore your data. In this ca, steps 1 and 3 may be all you need. If you are creating prentation graphics, you may want to finetune your graph by positioning it on the page, tting line styles and colors, adding annotations, and making other such improvements.
Step Typical Code
1. Prepare your data x = 0:0.2:12;
y1 = besl(1,x);
y2 = besl(2,x);
y3 = besl(3,x);
2. Select a window and position a plot region within the window figure(1) subplot(2,2,1)
3. Call elementary plotting function h = plot(x,y1,x,y2,x,y3);
4. Select line and marker characteris tics t(h,'LineWidth',2,{'LineStyle'},{'';':';'.'}) t(h,{'Color'},{'r';'g';'b'})
5. Set axis limits, tick marks, and grid lines axis([0 12 0.5 1]) grid on
6. Annotate the graph with axis labels, legend, and text xlabel('Time')
ylabel('Amplitude')
legend(h,'First','Second','Third') title('Besl Functions')
[y,ix] = min(y1);
text(x(ix),y,'First Min\rightarrow',... 'HorizontalAlignment','right')
7. Export graph print depsctiffr200 myplothdx
ü Plot function
plot(X,Y): plots vector Y versus vector X. If X or Y is a matrix, then the vector is plotted versus the rows or columns of the matrix, whichever line up.
It can be ud to plot of a curve expresd in explicit scheme or parameter reprentation.出国留学条件
>> x = [1 2 3 4 5 6]; y = [11.5 23 1 7];
>> plot(x, y);
>> plot(a); %plot six lines (1, 1); (2, 4); (3, 9); (4, 16); (5, 25); (6, 36)
Plot sin x over [0,2]p with title and grid.
>> t = 0:pi/100:2*pi;
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>> y = sin(t);
>> plot(t,y)
中医考研科目>> title (‘Plot of sinx vs x’) %titled‘Plot of sinx vs x’
>> xlabel(‘x 轴’); ylabel(‘sinx’) % adds text beside the Xaxis & Yaxis …
on the current axis
>> grid on
Plot the curve with sin ,cos x a mt y a nt == over [0,2] t p Î while a=8, m=2 and n=5.
>> t = linspace(0,2*pi);
% generates a row vector of 100 linearly equally spaced… points between 0 and 2p . >> a=8;
>> m=2;
>> n=5;
>> x = a*sin(m*t);
>> y = a*cos(n*t);creamer
>> plot (x, y, ‘b’) % color b lue, line style ‘’
记录英文ü Polar Plots
polar(THETA, RHO) makes a plot using polar coordinates of the angle THETA, in radians, versus the radius RHO.
>> g=0.5;
>> theta = linspace(0,2*pi,51); %generates 51 linearly equally spaced points…
between 0 and 2p .
>> gain = 2*g*(1+cos(theta));
>> polar (theta, gain, ‘r’) %color r ed, line style solid‘’
>> title (‘\bf Gain versus angle \theta ’); %boldface, \theta will be display as q
ü Ezplot Function Easy to u function plotter
It is usually ud to plot a curve expresd in implicit formula.
ezplot(FUN) plots the function FUN(X) over the default domain 2*pi < X < 2*pi.
ezplot (FUN,[A,B]) plots FUN(X) over A < X < B.
Plot the function 2
21 x x -+ , over [2,2] x p p Î- . >> ezplot('x^2 2*x + 1');
Plot 444
2 x y += , over ,[2,2] x y Î- . >> ezplot(‘x.*4+ y.^42^4’, [4,4])
ü Plot3 Function
Plot lines and points in 3D space.
plot3(x,y,z), where x, y and z are three vectors of the same length, plots a line in 3space through the points who coordinates are the elements of x, y and z.
plot3 (X,Y ,Z), where X, Y and Z are three matrices of the same size, plots veral lines obtained from the columns of X, Y and Z.
V arious line types, plot symbols and colors may be obtained with plot3 (X,Y ,Z,s) where s is a 1, 2 or 3 character string made from the characters listed under the plot3 command.
>> t = 0:pi/50:10*pi; >> plot3(sin(t),cos(t),t);英语专业网
