Scilab Function
Last update : 16/8/39991387
interp1 - one_dimension interpolation
function
Calling Sequence
- [yp]=interp1(x, y,xp [,
method,[extrapolation]])
Parameters
-
xp: reals scalar, vector or matrix (or hypermatrix)
-
x: reals vector
-
method: (optional) string defining the interpolation method
-
extrapolation: (optional) string, or real value defining the yp(j) components
for xp(j) values outside [x1,xn] interval.
-
yp: vector, or matrix (or hypermatrix)
Description
Given (x,y,xp), this function performs the yp components
corresponding to xp by the interpolation(linear by default) defined by x
and y.
If yp is a vector then the length of xp is equal to the
length of yp, if yp is a matrix then
xp have the same length than the length of each columns of
yp, if yp is a hypermatrix then the length of xp
have the same length than the first dimension of yp.
If size(y)=[C,M1,M2,M3,...,Mj] and size(xp)=[N1,N2,N3,...,Nk] then
size(yp)=[N1,N2,..,Nk,M1,M2,...Mj] and length of x must be equal to
size(y,1)
The method parameter sets the evaluation rule for
interpolation
"linear": the interpolation is defined by linear method (see
interpln)
"spline": the interpolation is defined by cubic spline interpolation ( see
splin , interp)
"nearest": for each value xp(j), yp(j) takes the value or y(i)
corresponding to x(i) the nearest neighbor of xp(j)
The extrapolation parameter sets the evaluation rule for
extrapolation, i.e for xp(i) not in [x1,xn] interval
"extrap": the extrapolation is performed by the defined method.
yp=interp1(x,y,xp,method,"extrap")
real value: you can choose a real value for extrapolation, in this way yp(i)
takes this value for xp(i) not in [x1,xn] interval, for example 0 (but
also nan or inf). yi=interp1(x,y,xp,method, 0)
by default: the extrapolation is performed by the defined method (for spline
method), and by nan for linear and nearest methods.
yp=interp1(x,y,xp,method)
Examples
x=linspace(0,3,20);
y=x^2;
xx=linspace(0,3,100);
yy1=interp1(x,y,xx,'linear');
yy2=interp1(x,y,xx,'spline');
yy3=interp1(x,y,xx,'nearest');
plot(xx,[yy1;yy2;yy3],x,y,'*')
xtitle('interpolation of square function')
legend(['linear','spline','nearest'],a=2)
See Also
interp, interpln, splin,
Author
F.B