哪为大哥有三次样条插值MATLAB函数的程序啊,给小弟发个啊,急用!如题!就这多分了,全部送上!

Question

哪为大哥有三次样条插值MATLAB函数的程序啊,给小弟发个啊,急用!
如题!就这多分了,全部送上!

Answer 1

matlab自带三次样条的程序啊
>> help spline
SPLINE Cubic spline data interpolation.
YY = SPLINE(X,Y,XX) uses cubic spline interpolation to find YY,the values
of the underlying function Y at the points in the vector XX.The vector X
specifies the points at which the data Y is given.If Y is a matrix,then
the data is taken to be vector-valued and interpolation is performed for
each column of Y and YY will be length(XX)-by-size(Y,2).
PP = SPLINE(X,Y) returns the piecewise polynomial form of the cubic spline
interpolant for later use with PPVAL and the spline utility UNMKPP.
Ordinarily,the not-a-knot end conditions are used.However,if Y contains
two more values than X has entries,then the first and last value in Y are
used as the endslopes for the cubic spline.Namely:
f(X) = Y(:,2:end-1),df(min(X)) = Y(:,1),df(max(X)) = Y(:,end)
Example:
This generates a sine curve,then samples the spline over a finer mesh:
x = 0:10; y = sin(x);
xx = 0:.25:10;
yy = spline(x,y,xx);
plot(x,y,'o',xx,yy)
Example:
This illustrates the use of clamped or complete spline interpolation where
end slopes are prescribed.Zero slopes at the ends of an interpolant to the
values of a certain distribution are enforced:
x = -4:4; y = [0 .15 1.12 2.36 2.36 1.46 .49 .06 0];
cs = spline(x,[0 y 0]);
xx = linspace(-4,4,101);
plot(x,y,'o',xx,ppval(cs,xx),'-');
See also INTERP1,PPVAL,SPLINES (The Spline Toolbox).