ENG1060 Lecture Notes - Lecture 2: Contour Line
30 May 2018
School
Department
Course
Professor
!"#$$%&'()*$*
Allows&faster,&easier interpretation&of&more&information
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Easier&to&characterise&trends
Increasing/decreasing&with&increasing&x
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No.&of&max&and&min
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plot(x,y)
x&must&be&indep,&y&must&be&dep
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Variables&must&be&same&length
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Also&has&optional&arguments,&like:
Title,&xlabel,&ylabel
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Line&colour,&type,&width
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Marker&colour,&symbol,&size
plot(x,y1,'rs')
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hold on
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plot(x,y2,'kx')
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plot(x,y3,'bo')
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'rs'&>>>&red&squares
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'kx'&>>>&black&crosses
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'bo'&>>>&blue&circles
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**HAVE&TO&USE"ATION&MARKS&(SINGLE)
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RGB&triplets&and&linewidth
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Markersize,&Markerfacecolor,&Markeredgecolor
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Multiple&plots&can&be&drawn&in&same&figure
plot(x1,y1,x2,y2)
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+,%"$-%&(.,&/$%#&0
figure -creates&a&new&figure&window
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close all -closing&all&opened&figure&windows
Use&at&the&top&of&script&files
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hold on -to&hold&(not&overwrite)¤t&figure&window
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If&using&two&plot&commands&in&sequence,&first&will&be&overridden&unless&
you&use&this
Also&hold&off
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grid on -turn&on&grid&axes
Also&grid&off
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legend -turn&on&legend&with&a&key
Use&when&plotting&multiple&curves&in&same&figure
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subplot(rows, columns, panel no./index) -multiple&plot&
windows&in&a&figure&window&-separated&frm&each&other&in&separate&boxes
subplot(3, 1, 1)
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plot(x,y1,'b')
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xlabel('x')
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ylabel('y1')
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subplot(3, 1, 2)
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xlabel('x')
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ylabel('y2')
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axis([ xmin xmax ymin ymax]) -setting&range&of&x&and&y&axes•
12(3"#$$%&'(.,&/$%#&0(4*5*(6#",7809
plot3(x,y,z) -3D&line&plot•
mesh(x,y,z) -mesh&plot•
surf(x,y,z) -surface&plot•
contour(z,number_of_lines) -contour&plot•
Helix:&
t = linspace(0, 10*pi, 200);
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plot3(sin(t), cos(t), t);
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xlabel('sin(t)');
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ylabel('cos(t)');
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zlabel('t');
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title('An example helix');
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grid on;
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3D&peak:
[x,y] = meshgrid(-2:0:2:2);
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z = exp(-.^2 -y.^2);
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mesh(x,y,z);
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xlabel('x');
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ylabel('y');
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zlabel('z');
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title('An example peak');
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grid on;
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If&surface of&peak,&same&thing&except
surf(x,y,z,50);
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title('An example surface of peak');
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If&viewing&contours of&peak,&same&thing&except
contour(x,y,z,50);
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title('Example contours of a peak');
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Week$2:$Plotting
Tuesday,& 1&August& 2017
11:09
Document Summary
No. of max and min plot(x,y) x must be indep, y must be dep. Marker colour, symbol, size plot(x,y1,"rs") hold on plot(x,y2,"kx") plot(x,y3,"bo") Multiple plots can be drawn in same figure plot(x1,y1,x2,y2) Built-in functions figure - creates a new figure window close all - closing all opened figure windows. Use at the top of script files hold on - to hold (not overwrite) current figure window. If using two plot commands in sequence, first will be overridden unless you use this. Also hold off grid on - turn on grid axes. Also grid off legend - turn on legend with a key legend - turn on legend with a key. 3d plotting functions (aka volumes) plot3(x,y,z) - 3d line plot mesh(x,y,z) - mesh plot surf(x,y,z) - surface plot contour(z,number_of_lines) - contour plot. Helix: t = linspace(0, 10*pi, 200); plot3(sin(t), cos(t), t); xlabel("sin(t)"); ylabel("cos(t)"); zlabel("t"); title("an example helix"); grid on;
