It calculates the value of the function or expression

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Unformatted text preview: r special case. The function x → 1/(x − 1)2 has a singularity at x = 1. > plot( 1/(x-1)^2, x=-5..6 ); 250000 200000 150000 100000 50000 –4 –2 0 2 4 6 x In the previous plot, all the interesting details of the graph are lost because there is a spike at x = 1. The solution is to view a narrower range, perhaps from y = −1 to 7. > plot( 1/(x-1)^2, x=-5..6, y=-1..7 ); 5.1 Graphing in Two Dimensions • 113 7 6 5 y 4 3 2 1 –4 –2 0 –1 2 x 4 6 The tangent function has singularities at x = integer. > plot( tan(x), x=-2*Pi..2*Pi ); π 2 + πn, where n is any 3000 2000 1000 –6 –4 –2 2 x 4 6 To see the details, reduce the range to y = −4 to 4. > plot( tan(x), x=-2*Pi..2*Pi, y=-4..4 ); 4 3 y2 1 –6 –4 –2 0 –1 –2 –3 –4 2 x 4 6 Maple draws almost vertical lines at the singularities. To specifiy a plot without these lines, use the discont=true option. 114 • Chapter 5: Plotting > plot( tan(x), x=-2*Pi..2*Pi, y=-4..4, discont=true ); 4 3 y2 1 –6 –4 –2 0 –1 –2 –3 –4 2 x 4 6 Multiple Functions To graph more than one function in the same plot, give plot a list of functions. > plot( [ x, x^2, x^3, x^4 ], x=-10..10, y=-10..10 ); 10 8 6 y 4 2 –10 –8 –6 –4 –2 0 –2 –4 –6 –8 –10 2 4 x 6 8 10 > f := x -> piecewise( x<0, cos(x), x>=0, 1+x^2 ); f := x → piecewise(x < 0, cos(x), 0 ≤ x, 1 + x2 ) > plot( [ f(x), diff(f(x), x), diff(f(x), x, x) ], > x=-2..2, discont=true ); 5.1 Graphing in Two Dimensions • 115 5 4 3 2 1 –2 –1 0 –1 1 x 2 This technique also works for parametrized plots. > plot( [ [ 2*cos(t), sin(t), t=0..2*Pi ], > [ t^2, t^3, t=-1..1 ] ], scaling=constrained ); 1 0.5 –2 –1 –0.5 –1 1 2 To distinguish between several graphs in the same plot, use different line styles such as solid, dashed, or dotted. Use the linestyle option where linestyle=SOLID for the first function, sin(x)/x, and linestyle=DOT for the second function, cos(x)/x. > plot( [ sin(x)/x, cos(x)/x ], x=0..8*Pi, y=-0.5..1.5, > linestyle=[SOLID,DOT] ); 1.4 1.2 1 y0.8 0.6 0.4 0.2 0 –0.2 –0.4 5 10 x 15 20 25 116 • Chapter 5: Plotting You can also change the line style by using the standard menus and the context-sensitive menus. Similarly, specify the colors of the graphs by using the color option. Note that in this manual, the lines appear in two different shades of gray. > plot( [ [f(x), D(f)(x), x=-2..2], > [D(f)(x), (D@@2)(f)(x), x=-2..2] ], > color=[gold, plum] ); 4 3 2 1 0 –1 1 2 3 4 5 For more details on colors, refer to the ?plot,color help page. Plotting Data Points To plot numeric data, call pointplot in the plots package with the data in a list of lists of the form [[x1 , y1 ], [x2 , y2 ], . . . , [xn , yn ]]. If the list is long, assign it to a name. > data_list:=[[-2,4],[-1,1],[0, 0],[1,1],[2,4],[3,9],[4,16]]; data _list := [[−2, 4], [−1, 1], [0, 0], [1, 1], [2, 4], [3, 9], [4, 16]] > pointplot(data_list); 5.1 Graphing in Two Dimensions...
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This note was uploaded on 08/27/2012 for the course MATH 1100 taught by Professor Nil during the Spring '12 term at National University of Singapore.

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