科学计算科学计算 (24).pdf

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1、2-D curves in other coordinatesData distribution plotsVector fields plots4 4.3 3 OtherOther 2 2-D D PlotsPlots1.21.2-D Curves in Other CoordinatesD Curves in Other Coordinatessemilogx(x1,y1,LineSpec1,x2,y2,LineSpec2,)semilogy(x1,y1,LineSpec1,x2,y2,LineSpec2,)loglog(x1,y1,LineSpec1,x2,y2,LineSpec2,)(

2、1)Logarithmic coordinates The semilogx function creates semilog plot,logarithmic scales for the x-axis whilelinear scales for the y-axis.The semilogy function also creates semilog plot,logarithmic scales for the y-axiswhile linear scales for the x-axis.The loglog function plots x-and y-coordinates u

3、sing logarithmic scales on the x-axis and the y-axis.Exammple 1 Plot 1in lineal and logarithmic scales coordinate system.x=0:0.1:10;y=1./x;subplot(2,2,1)plot(x,y)title(plot(x,y);grid onsubplot(2,2,2)semilogx(x,y)title(semilogx(x,y);grid onsubplot(2,2,3)semilogy(x,y)title(semilogy(x,y);grid onsubplot

4、(2,2,4)loglog(x,y)title(loglog(x,y);grid onArgument theta indicates the angle in radians and rho indicates the radius value for each point.Argument LineSpec is the same as that of the plot function.1.21.2-D Curves in Other CoordinatesD Curves in Other Coordinates(2)Polar plotpolar(theta,rho,LineSpec

5、)t=0:pi/100:2*pi;r=1-sin(t);subplot(1,2,1)polar(t,r)subplot(1,2,2)t1=t-pi/2;r1=1-sin(t1);polar(t,r1)Example 2 Plot a heart-shaped curve.=1 2.Data Distribution Plots2.Data Distribution PlotsBar plotHistogramPie chartScatter plot(1)Bar plot bar graphThe bar Function Create a vertical bar graphThe barh

6、 FunctionCreate a horizontal bar graph2.Data Distribution Plots2.Data Distribution Plots2.Data Distribution Plots2.Data Distribution Plots(1)Bar plot bar graphbar(y,style)Create a bar graph with one bar for each element in y.Argument style can be specified by one of these values.groupedDisplay each

7、group as adjacent bars that are centered around theircorresponding x value.stacked Display each group as one multicolored bar.The length of a bar is the sum ofthe elements in the group.y=1,2,3,4,5;1,2,1,2,1;5,4,3,2,1;subplot(1,2,1)bar(y)title(Group)subplot(1,2,2)bar(y,stacked)title(Stack)1 2 3 4 51

8、2 1 2 15 4 3 2 1Matrix YExample 3 Create a bar graph.2.Data Distribution Plots2.Data Distribution Plots(1)Bar plot bar graphbar(x,y,style)Specify x as a vector of unique values,and specify y as a matrix.The length of x must equal the length of at least one dimension of y.The other dimension of y con

9、tains values for the different series of bars.Example 4 The following table shows the household appliances sales data of a company in January 2015-2017.Draw a statistical graph with the data in the table.x=2015,2016,2017;y=68,80,115,98,102;75,88,102,99,110;81,86,125,105,115;bar(x,y)title(Group);2.Da

10、ta Distribution Plots2.Data Distribution Plots(1)Bar plot Histogram plotThe hist functionCreate a histogram plot in linear coordinate systemThe rose functionCreate a histogram plot in polar coordinate systemThe y is grouped into equally spaced bins between the minimum and maximum values of y.And the

11、 number of elements in the bin is computed,the height of each rectangle indicates the number of elements in the bin.Argument x is used to specify bin locations or categories.If x is a scalar,sorts y into the number of bins specified by x.If x is a vector,each element in vector x specifies each bin c

12、enter,and the length of the vector x is equal to the number of bins.2.Data Distribution Plots2.Data Distribution Plots(1)Bar plot Histogram plothist(y)hist(y,x)y=randn(500,1);subplot(2,1,1);hist(y);title(Histogram of Gaussian Distribution);subplot(2,1,2);x=-3:0.2:3;hist(y,x);title(Histogram of Inter

13、val Center Point)Example 5 Create a histogram of Gaussian distribution.2.Data Distribution Plots2.Data Distribution Plots(1)Bar plot Histogram plotrose(theta,x)Create a histogram plot in polar coordinates by sorting the values in theta into equally spaced bins.Specify the values in radians.Argument

14、x is used to specify the number of bins.y=randn(500,1);theta=y*pi;rose(theta)title(Histogram in Polar Scale)Example 6 Plot an angle histogram of Gaussian distribution in polar scale.(2)Area chartThe pie FunctionDraw pie chart The area FunctionCreate filled area 2-D plot2.Data Distribution Plots2.Dat

15、a Distribution Plots2.Data Distribution Plots2.Data Distribution Plots(2)Area chart The pie Functionpie(x,explode)Argument x stores the data to be plotted.The pie function offsets slices for the nonzero elements in the explode from the pie.Example 7 The number of excellent,good,medium,pass and fail

16、in an examination are 5,17,23,9,4 respectively.Make statistic analysis on an examination using pie chart.score=5,17,23,9,4;ex=0,0,0,0,1;pie(score,ex)legend(excellent,good,medium,pass,.fail,location,eastoutside)Note:The location option of the legend function sets the legend location.eastoutside posit

17、ions thelegend to the right of the axes.2.Data Distribution Plots2.Data Distribution Plots(3)Area chart The scatter function The stairs function The stem functionscatter(x,y,options,filled)Argument x and y are used to locate circles.Options is used to specify circle sizes,colors and the marker type.

18、If each marker have a face,you can use the filled option to fill the interior of the markers.When the option is omitted,the markers are hollow.（3）Discrete Data Plots scatter2.Data Distribution Plots2.Data Distribution PlotsExample 8 Draw a heart-shaped curve using scatter plot.The parameter equation

19、 of the curve is as follows:t=0:pi/50:2*pi;x=16*sin(t).3;y=13*cos(t)-5*cos(2*t)-2*cos(3*t)-cos(4*t);scatter(x,y,rd,filled)=163=13 5cos(2)2cos(3)cos(4)3.Vector Fields Plots3.Vector Fields PlotsThe compass functionThe feather functionThe quiver functionThe quiver functionquiver(x,y,u,v)A quiver plot d

20、isplays velocity vectors as arrows with components(u,v)at the points(x,y).The matrices or vectors x,y,u,and v must all be the same size.If x and y are omitted,the vectors will be drawn at equally spaced points in the x-y plane.3.Vector Fields Plots3.Vector Fields PlotsA=4,5;B=-10,0;C=A+B;hold on;quiver(0,0,A(1),A(2);quiver(0,0,B(1),B(2);quiver(0,0,C(1),C(2);text(A(1),A(2),A);text(B(1),B(2),B);text(C(1),C(2),C);axis(-12,6,-1,6)grid onExample 9 Given vector A and vector B.Find A+B,and express it with vector plot.