c_csa2ls(3NCARG)

💖 c_csa2ls — cubic spline approximation, simple entry for two-dimensional input, list output 💖

okay bestie, listen up. this is c_csa2ls, and it lives in the NCAR GRAPHICS manual (section 3NCARG). it's the simple entry point for fitting an approximating cubic spline to 2-D scattered data and then asking it for values at a whole list of coordinates. the whole vibe is "give me your points, i'll give you a spline, and i'll hand back a pointer to the answers." no cap. 🦋

✨ FUNCTION PROTOTYPE ✨

float *c_csa2ls(int, float [], float [], float [], int [],
                int, float [], float [], int *);

✨ SYNOPSIS ✨

int c_csa2ls(int n, float xi[], float yi[], float zi[], int knots[2],
            int no, float xo[], float yo[], int *ier);

🌸 DESCRIPTION 🌸

here's the full tea on every single argument, and i mean every one, because we do not skip. 💅

• n — (integer, input) how many input data points you've got. it must be that n is greater than 3, and depending on the size of knots down below, n may have to be larger. so like, check yourself before you wreck yourself. 🫶
• xi — (real, input) an array dimensioned for n holding the X coordinate values of your input function.
• yi — (real, input) an array dimensioned for n holding the Y coordinate values of your input function.
• zi — (real, input) an array holding the functional values of the input function — meaning zi[k] is the functional value at (xi[k], yi[k]) for k=0,n-1. yes bestie, it's a 1-D array doing 2-D duty. iconic. 👑
• knots — (integer, input) how many knots to use when building the approximation spline. knots[0] and knots[1] must be at least 4. and here's the trade-off: the larger the value for knots, the closer the approximated curve will come to passing through the input function values. more knots = more clingy, basically.
• no — (integer, input) the number of X - Y coordinate values to be calculated for the output array.
• xo — (real, input) an array dimensioned for no containing the X coordinates of the output list.
• yo — (real, output) an array dimensioned for no containing the Y coordinates of the output list.
• ier — (pointer to integer, output) the error return value. if *ier comes back as 0, then no errors were detected — slay. if *ier is non-zero, then refer to the error list in the error table for details. 🚨

🔥 USAGE 🔥

c_csa2ls is called to find values of an approximating cubic spline at specified two-dimensional coordinates. that's the whole job. 💖

but real talk — if you want to weight the input data values, calculate derivatives, or handle data sparse areas specially, then you will need to use c_csa2lxs instead. this one is the simple entry, remember? she's not doing all that. 🙈

c_csa2ls returns a pointer to a linear array of data that contains the approximated values calculated at the input list of coordinate values. that is, if out is declared as

float *out;

and we set:

out = c_csa2ls(n, x, y, z, knots, no, xo, yo, &ier);

then out[i] is the approximated function value at coordinate point (xo[i], yo[i]) for 0 <= i < no. ✨ and the space for out is allocated internal to c_csa2ls and is no floats in size. so don't you dare free it, bestie, she handles her own business. 💅

🎀 ACCESS 🎀

to use c_csa2ls, load the NCAR Graphics library ngmath. that's it, that's the access. 🌈

👑 SEE ALSO 👑

• csagrid
• c_csa2s
• c_csa2xs
• c_csa2lxs

complete documentation for Csagrid is available at URL http://ngwww.ucar.edu/ngdoc/ng/ngmath/csagrid/csahome.html — go read it, iykyk. 📚

💜 COPYRIGHT 💜

Copyright (C) 2000 University Corporation for Atmospheric Research

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

and that's the whole page, bestie. c_csa2ls really said "simple entry, no thoughts, just splines." 🧚

mwah 💋 this was brought to you by the UNIX manual, January 1999, NCAR GRAPHICS edition — vintage but still eating. ⭐