Basics of Plotting in Matlab Matlab 繪圖基礎(chǔ)知識

PlottinginMatlab

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BasicsofPlottinginMatlabGSF3/22/12

TableofContents

BasicOverview

Syntax

LabelingAxes

Legends

ManipulatingAxes

Subplots

MultipleY-Axes

Statistics

3-Dplots

AdditionalResources

BasicOverview

Tousethe‘plot’functioninMatlab,youshouldfirstmakesurethatthematrices/vectorsyouaretryingtouseareofequaldimensions.Forexample,ifIwantedtoplotvectorX=[3927]overtime,myvectorfortimewouldalsoneedtobea1x3vector(i.e.t=[123]).

Syntax

Toplottheexamplevectorsaboveinanewfigure:

clearall %clearallpreviousvariables

X=[3927];%mydependentvectorofinterestt=[123]; %myindependentvector

figure %createnewfigureplot(t,X)

LabelingAxes

Togivetheabovefigureatitleandaxislabels:

title(‘PlotofDistanceoverTime’) %titleylabel(‘Distance(m)’) %labelforyaxisxlabel(‘Time(s)’) %labelforxaxis

Legends

Ifyouhaveplottedmultipledependentvectorsonthesameplotandwanttodistinguishthemfromeachotherviaalegend,thesyntaxisverysimilartotheaxislabelingabove.Itisalsopossibletosetcolorsforthedifferentvectorsandtochangethelocationofthelegendonthefigure.

Example:

clearall

X=[3927]; %dependentvectorsofinterest

Y=[1086];

Z=[444];

t=[123]; %independentvectorfigure

holdon %allowallvectorstobeplottedinsame

%figure

plot(t,X,‘blue’,t,Y,‘red’,t,Z,‘green’)

title(‘PlotofDistanceoverTime’) %titleylabel(‘Distance(m)’) %labelforyaxisxlabel(‘Time(s)’) %labelforxaxis

legend(‘Trial1’,‘Trial2’,‘Trial3’)legend(‘Location’,‘NorthWest’)%movelegendtoupperleft

Subplots

Itcansometimesbeusefultodisplaymultipleplotsonthesamefigureforcomparison.Thiscanbedoneusingthesubplotfunction,thattakesargumentsfornumberofrowsofplots,numberofcolumnsofplots,andplotnumbercurrentlybeingplotted:

Example:

clearallcloseall

%subplot(nrows,ncols,plot_number)

x=0:.1:2*pi; %xvectorfrom0to2*pi,dx=0.1

subplot(2,2,1); %plotsinefunctionplot(x,sin(x));

subplot(2,2,2); %plotcosinefunctionplot(x,cos(x));

subplot(2,2,3) %plotnegativeexponentialfunctionplot(x,exp(-x));

subplot(2,2,4); %plotx^3plot(x,x.^3);

Plottingin3-D

TherearealsowaystoplotinmultipledimensionsinMatlab*.Onetypeof3-Dplotthatmaybeusefulisasurfaceplot,whichrequiresyoutogeneratesomekindofx-yplaneandthenapplya3rdfunctionasthezdimension.

Example:

clearallcloseall

[x,y]=meshgrid([-2:.2:2]); %setup2-Dplane

Z=x.*exp(-x.^2-y.^2); %plot3rddimensiononplane

figure

surf(x,y,Z,gradient(Z)) %surfaceplot,withgradient(Z)

%determiningcolordistribution

colorbar %displaycolorscale,canadjust

%locationsimilarlytolegend

Seereferencematerialforamoredetaileddescriptionof3-Dplottinganditsapplications.

AdditionalMatlabReferences

InMatlab,type‘help(insertphrase)’togetdescriptionofcommandfunctionality

Ex.helpplot givesinstructionsforwhatargumentstopasstheplotfunction,howtouseit,whatoutputtoexpect,etc.

Matlabwebsite:

/help/techdoc/

Usef