Please enable JavaScript to view this site.

Knowledge Base

Returns the Chebyshev interpolation coefficients. The amplitude of the coefficients decreases exponentially and the last coefficient offers an estimate of the relative accuracy of the interpolation.

 

Supported Product: FDTD, MODE

 

Syntax

Description

coeff=dcht(f,option);

Returns the Chebyshev interpolation coefficients of a sampled function f. The function f must be sampled on a Chebyshev roots grid.

 

Option:

If option=1 is selected, the vector x will not include the endpoints

If option=2 is selected, the vector x will include the endpoints

 

Example

This example shows how to obtain interpolation coefficients from a sampled function:

Nc = 15;         # Number of sample points

xmin = 0;

xmax = 1;

x = chpts(xmin,xmax,Nc,1); # Returns Chebyshev roots grid on interval between xmin and xmax

f = exp(1i*2*pi*x);    # Function sampling using Chebyshev grid

coeff = dcht(f,1);     # Get interpolation coefficients

?abs(coeff);

result: 

0.304242  

0.569231  

0.970868  

0.666917  

0.302849  

0.104282  

0.0290919  

0.00684063  

0.00139224  

0.000250007  

4.01899e-005  

5.85025e-006  

7.78278e-007  

9.53372e-008  

1.094e-008      

 

See Also

chpts, chebin, icht, chebpol, chebpol1

Copyright Lumerical Inc. | Privacy | Site Map