PyPspline examples

1-D interpolation using not-a-knot boundary conditions: import Numeric as N from pypspline.pspline1_r8 import pspline eps = 1.e-10 # original data nx = 11 dx = 1./(nx-1) x = N.arange(0, 1.+eps, dx) y = x**3/3 # new grid nxi = 2*(nx-1)+1 dxi = 1./(nxi-1) xi = N.arange(0,1.+eps, dxi) spl = pspline(x) # compute spline coefficients spl.setup(y) # interpolate yi = spl.interp(xi) # 1st derivative ypi = spl.derivative(1, xi) # 2nd derivative yppi= spl.derivative(2, xi) </plaintext> </li> <li> 2-D interpolation using periodic boundary conditions: <plaintext> import Numeric as N from pypspline.pspline2_r8 import pspline, griddata eps = 1.e-10 # original data nx, ny = 11, 21 dx, dy = 1./(nx-1), 2*N.pi/(ny-1) x = N.arange(0, 1.+eps , dx) y = N.arange(0, 2*N.pi+eps, dy) xx, yy = griddata(x, y) f = xx**3 * N.cos(yy) # new grid nxi, nyi = 2*(nx-1)+1, 2*(ny-1)+1 dxi, dyi = 1./(nxi-1), 2*N.pi/(nyi-1) xi = N.arange(0, 1.+eps, dxi) yi = N.arange(0, 2*N.pi+eps, dyi) # not-a-knot in x, periodic in y spl = pspline(x,y, bcs1=None, bcs2=1) # compute spline coefficients spl.setup(f) # interpolate fi = spl.interp(xi, yi) # df/dx fxi = spl.derivative(1,0, xi, yi) # d^2f/dy^2 fyyi= spl.derivative(0,2, xi, yi) </plaintext> </li> <li> 3-D interpolation with mixed slope/second derivative conditions: <plaintext> import Numeric as N from pypspline.pspline3_r8 import pspline, griddata eps = 1.e-10 # original data nx, ny, nz = 11, 21, 31 dx, dy, dz = 1./(nx-1), 2*N.pi/(ny-1), 2./(nz-1) x = N.arange(0, 1.+eps , dx) y = N.arange(0, 2*N.pi+eps, dy) z = N.arange(0, 2.+eps , dz) xx, yy, zz = griddata(x, y, z) # function to interpolate f = xx**3 * N.cos(yy) + zz**3/3 # new grid nxi, nyi, nzi = 2*(nx-1)+1, 2*(ny-1)+1, 2*(nz-1)+1 dxi, dyi, dzi = 1./(nxi-1), 2*N.pi/(nyi-1), 2./(nzi-1) xi = N.arange(0, 1.+eps, dxi) yi = N.arange(0, 2*N.pi+eps, dyi) zi = N.arange(0, 2.+eps , dzi) # not-a-knot in x, periodic in y # slope @ zmin, 2nd derivative @ zmax spl = pspline(x,y,z, bcs1=None, bcs2=1, bcs3=(1,2)) # set boundary condition df/dz @ zmin # (note indexing order: [iz, iy, ix]) spl.bcval3min = zz[ 0,:,:]**2 # set boundary condition d^2f/dz^2 @ zmax spl.bcval3max = 2*zz[-1,:,:] # compute spline coefficients spl.setup(f) # interpolate fi = spl.interp(xi, yi, zi) </plaintext> </li> <hr> <address><a href="mailto:Alexander.Pletzer@noaa.gov">Alexander Pletzer</a></address>   Last modified: Thu Apr 1 08:48:17 EST 2004  <p> <a href="http://sourceforge.net"> <img src="http://sourceforge.net/sflogo.php?group_id=28885&type=5" width="210" height="62" border="0" alt="SourceForge Logo"></a> </body> </p> </html>