This is machine translation

Translated by Microsoft
Mouse over text to see original. Click the button below to return to the English verison of the page.


Spline curve by uniform subdivision




spcrv(c,k) provides a dense sequence f(tt) of points on the uniform B-spline curve f of order k with B-spline coefficients c. Explicitly, this is the curve

f:t|j=1nB(tk/2|j,...,j+k) c(j), k2tn+k2

with B(·|a,...,z) the B-spline with knots a,...,z, and n the number of coefficients in c, i.e., [d,n] equals size(c).

spcrv(c) chooses the order k to be 4.

spcrv(c,k,maxpnt) makes sure that at least maxpnt points are generated. The default value for the maximum number of sites tt to be generated is 100.

The parameter interval that the site sequence tt fills out uniformly is the interval [k/2 .. (n-k/2)].

The output consists of the array f(tt).


The following would show a questionable broken line and its smoothed version:

points = [0 0 1 1 0 -1 -1 0 0 ;
        0 0 0 1 2 1 0 -1 -2]; 
values = spcrv(points,3); 
hold on, plot(values(1,:),values(2,:)), hold off

More About

collapse all


Repeated midpoint knot insertion is used until there are at least maxpnt sites. There are situations where use of fnplt would be more efficient.

See Also

Was this topic helpful?