points = fnplt(f,...)
[points, t] = fnplt(f,...)
fnplt(f) plots the function,
f, on its basic interval.
If f is univariate, the following is plotted:
If f is scalar-valued, the graph of f is plotted.
If f is d-vector-valued with d > 2, the space curve given by the first three components of f is plotted.
If f is bivariate, the following is plotted:
If f is scalar-valued, the graph
of f is plotted (via
If f is 2-vector-valued, the image in the plane of a regular grid in its domain is plotted.
If f is d-vector-valued
with d > 2, then the parametric surface given
by the first three components of its values is plotted (via
If f is a function of more than two variables, then the bivariate function, obtained by choosing the midpoint of the basic interval in each of the variables other than the first two, is plotted.
permits you to modify the plotting by the specification of additional
input arguments. You can place these arguments in whatever order you
like, chosen from the following list:
A character vector that specifies
a plotting symbol, such as
the default is
A scalar to specify the linewidth;
the default value is
A character vector that starts
with the letter
'j' to indicate that any jump in
the univariate function being plotted should
actually appear as a jump. The default is to fill in any jump by a
A vector of the form
to indicate the interval over which to plot the
f. If the function in
f is m-variate,
then this optional argument must be a cell array whose ith entry specifies
the interval over which the ith argument is to
vary. In effect, for this
arg, the command
the same effect as the command
The default is the basic interval of
An empty matrix or character vector, to indicate use of default(s). You will find this option handy when your particular choice depends on some other variables.
[points, t] = fnplt(f,...)
also returns, for a vector-valued
f, the corresponding
t of parameter values.
The basic interval for f in B-form is the
interval containing all the knots. This means that, e.g., f is
sure to vanish at the endpoints of the basic interval unless the first
and the last knot are both of full multiplicity k,
with k the order of the spline f.
Failure to have such full multiplicity is particularly annoying when f is
a spline curve, since the plot of that curve as produced by
then bound to start and finish at the origin, regardless of what the
curve might otherwise do.
Further, since B-splines are zero outside their support, any function in B-form is zero outside the basic interval of its form. This is very much in contrast to a function in ppform whose values outside the basic interval of the form are given by the extension of its leftmost, respectively rightmost, polynomial piece.
x of evaluation points is generated
by the union of:
101 equally spaced sites filling out the plotting interval
Any breakpoints in the plotting interval
The univariate function f described
f is evaluated at these
points. If f is real-valued, the points (x,f(x))
are plotted. If f is vector-valued, then the first
two or three components of f(x)
The bivariate function f described by
evaluated on a 51-by-51 uniform grid if f is scalar-valued
or d-vector-valued with d >
2 and the result plotted by
In the contrary case, f is evaluated along the
meshlines of a 11-by-11 grid, and the resulting planar curves are