c_cssgridd(3NCARG)

💖 c_cssgridd — tension spline interpolation on a sphere 💖

okay bestie, sit down, hydrate, because we're about to talk about c_cssgridd from the NCAR GRAPHICS manual (that's 3NCARG, iykyk). it's giving ✨math✨ but make it cute. no cap, this one is a whole vibe. 🦋

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✨ FUNCTION PROTOTYPE ✨

here's the exact signature, copy it like your life depends on it (it does):

double *c_cssgridd(int, double [], double [], double [],
                 int, int, double [], double [], int *);

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🌸 SYNOPSIS 🌸

and here it is with the actual argument names, because we're extra like that:

double *c_cssgridd (n, rlat, rlon, f, ni, nj, plat, plon, ier)

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🎀 DESCRIPTION 🎀

every single argument, no skips, periodt:

• n — the number of input data points you're feeding in. and it has to be n > 2, okay?? like, we need at least three, that's the floor, that's the bare minimum, bestie.
• rlat — an array holding the latitudes of your input data, in degrees. ⚠️ big warning energy here: the first three points must not be collinear, meaning they cannot all lie on a common great circle. do not test this. she will know.
• rlon — an array with the longitudes of your input data, also in degrees. 💅
• f — the array of data values. f[i] is the functional value at (rlat[i],rlon[i]) for i = 0 to n-1. so like, index-matched, they're a set, they come as a group, do not separate them. 🫶
• ni — the number of latitudes in the interpolated grid you want back.
• nj — the number of longitudes in the interpolated grid. and here's the fun part: ni and nj can both be 1, which lets you interpolate at a single point. one point! main character energy, honestly. ⭐
• plat — an array of the latitudes of the points where you want the interpolated values computed. the values in plat should be in degrees. 🌈
• plon — an array of length nj containing the longitudes of the output grid lines. the values in plon should be in degrees too. consistent queen. 👑
• ier — the error return value, aka the vibe check. if *ier comes back as 0, then no errors were detected, we ate, we're slaying. if *ier is non-zero, then go refer to the error list in cssgrid_errors for the details. 🙈

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💜 USAGE 💜

you call c_cssgridd when you want to find an interpolating tension spline for randomly positioned data on a unit sphere. yes, a sphere. we're doing spherical geometry, we're doing it cute. 🌍

also, tiny flex: c_cssgridd is the double precision version of c_cssgrid. so if you want the double precision girlies, that's her. ✨

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🔥 RETURN VALUE 🔥

c_cssgridd returns a pointer to a linear array of data that holds the interpolated values at the user-specified lat/lon pairs. and the way it stores them?? as if it were a 2-dimensional C array with latitude as the first dimension and longitude as the second dimension. structured. organized. iconic. 💅

so if out is declared like this:

double *out;

and then we set:

out = c_cssgridd(n, rlat, rlon, f, nlat, nlon, plat, plon, &ier);

then out[i*nlon+j] is the interpolated function value at coordinate point (plat[i], plon[j]) for 0 <= i < nlat and 0 <= j < nlon. that's the indexing math, bestie, memorize it. 🧠✨

and the space for out is allocated internal to c_cssgridd, and it's nlat * nlon doubles in size. so don't you dare allocate it yourself, she's handling it, she's got it. 🫶

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🌟 ACCESS 🌟

to use c_cssgridd, you load the NCAR Graphics library ngmath. that's it, that's the whole trick. 🎀

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🦋 SEE ALSO 🦋

• c_cssgrid
• css_overview
• cssgrid_errors

and also!! complete documentation for Cssgrid is available at this URL:

http://ngwww.ucar.edu/ngdoc/ng/ngmath/cssgrid/csshome.html

go read it, bestie, it's right there. 💖

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👑 COPYRIGHT 👑

Copyright (C) 2000 University Corporation for Atmospheric Research

The use of this Software is governed by a License Agreement.

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okay that's the whole page, you're officially educated on c_cssgridd 💖✨ this was written up for the UNIX manual, May 2000, and yes she's been serving interpolation excellence since then. now go interpolate something cute. mwah. 💅🎀🦋