Sequence
Given an expression in x and a list containing three values, draws the line y=x, the plot of the function dened
by the expression over the domain dened by the interval between the last two values, and draws the cobweb
plot for the rst n terms of the sequence dened recursively by the expression (starting at the rst value).
Syntax: plotseq(f(Var), Var={Start, Xmin, Xmax}, Integern)
Example:
plotseq(1-x/2, x={3 -1 6}, 5) plots y=x and y=1–x/2 (from x=–1 to x=6), then draws the
rst 5 terms of the cobweb plot for u(n)=1-(u(n–1)/2, starting at u(0)=3
Implicit
Plots an implicitly dened curved from Expr (in x and y). Specically, plots Expr=0. Note the use of lowercase x
and y. With the optional x-interval and y-interval, plots only within those intervals.
Syntax: plotimplicit(Expr, [XIntrvl, YIntrvl])
Example:
plotimplicit((x+5)^2+(y+4)^2-1) plots a circle, centered at the point (-5, -4), with a radius of
1
Slopeeld
Plots the graph of the slopeeld for the dierential equation y’=f(x,y), where f(x,y) is contained in Expr.
VectorVar is a vector containing the variables. If VectorVar is of the form [x=Interval, y=Interval], then the
slopeeld is plotted over the specied x-range and y-range. Given xstep and ystep values, plots the slopeeld
segments using these steps. If Option is normalize, then the slopeeld segments drawn are equal in
length.
Syntax: plotfield(Expr, VectorVar, [xstep=Val, ystep=Val, Option])
Example:
plotfield(x*sin(y), [x=-6..6, y=-6..6],normalize) draws the slopeeld for
y'=x*sin(y), from -6 to 6 in both directions, with segments that are all of the same length.
ODE
Draws the solution of the dierential equation y’=f(Va1, Var2, ...) that contains as initial condition for the
variables Val1, Val2,... The rst argument is the expression f(Var1, Var2,...), the second argument is the vector
of variables, and the third argument is the vector of initial conditions.
Syntax: plotode(Expr, [Var1, Var2, ...], [Val1, Val2. ...])
Example:
plotode(x*sin(y), [x,y], [–2, 2]) draws the graph of the solution to y’=x*sin(y) that
passes through the point
(–2, 2) as its initial condition
List
Plots a set of n points and connects them with segments. The points are dened by a 2xn matrix, with the
abscissas in the rst row and the ordinates in the second row.
Syntax: plotlist(Matrix 2xn)
Example:
198 Chapter 9 Geometry
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