c_csa3lxs(3NCARG)

💖 c_csa3lxs — cubic spline approximation, expanded entry for three-dimensional input, list output 💖

okay bestie, welcome to the NCAR GRAPHICS manual page for c_csa3lxs, and no cap, this one is a whole mood. it's a C function, it lives in the ngmath world, and it is genuinely iconic. let's get into it 🦋

✨ FUNCTION PROTOTYPE ✨

float *c_csa3lxs(int, float [], float [], float [], float [],
                 float [], int [], float, int [],
                 int, float [], float [], float [], int *);

🌸 SYNOPSIS 🌸

float *c_csa3lxs(int n, float xi[], float yi[], float zi[], float ui[],
                 float wts[], int knots[3], float smth, int nderiv[3],
                 int no, float xo[], float yo[], float zo[], int *ier);

like… look at all those arguments. she's high maintenance but she delivers 💅

🎀 DESCRIPTION 🎀

okay so here's the full tea on every single argument, one by one, no skipping, we don't do that here:

• n — (integer, input) the number of input data points. bestie, it must be that n is greater than 3, and depending on the size of knots below, n may have to be even larger. so like, mind the vibes. 👑
• xi — (real, input) an array dimensioned for n containing the X coordinate values for the input function.
• yi — (real, input) an array dimensioned for n containing the Y coordinate values for the input function.
• zi — (real, input) an array dimensioned for n containing the Z coordinate values for the input function.
• ui — (real, input) an array containing the functional values of the input function — ui[k] is the functional value at (xi[k], yi[k], zi[k]) for k=0,n-1. periodt.
• wts — (real, input) an array containing weights for the ui values at the input values, that is, wts[l] is a weight for the value of ui[l] for l=0,n-1. if you do not desire to weight the input ui values, then set wts[0] to -1. the weights in the wts array are relative and may be set to any non-negative value. when c_csa3lxs is called, the weights are summed and the individual weights are normalized so that the weight sum is unity. math girlies rise up 🧚
• knots — (integer, input) the number of knots to be used in constructing the approximation spline. knots[0], knots[1], and knots[2] must be at least 4. the larger the value for knots, the closer the approximated curve will come to passing through the input function values. it's giving "the more you put in, the more you get out" 💀
• smth — (real, input) a parameter that controls extrapolation into data sparse regions. if smth is zero, then nothing special is done in data sparse regions. a good first choice for smth is 1. slay, start there.
• nderiv — (real, input) for each of the two coordinate direction, specifies whether you want functional values (nderiv=0), first derivative values (nderiv=1), or second derivative values (nderiv=2). for example, if nderiv[0]=1, nderiv[1]=1 and nderiv[2]=0, then the second order mixed partial with respect to X and Y would be computed. calculus girlies, this one's for you 😭
• no — (integer, input) the number of X - Y - Z 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.
• zo — (real, output) an array dimensioned for no containing the Z coordinates of the output list.
• ier — (pointer to integer, output) an error return value. if *ier is returned as 0, then no errors were detected — we love a clean run ✨. if *ier is non-zero, then refer to the error list in the error table for details. so like, read the error table, bestie, don't just panic. 🙈

💜 USAGE 💜

so c_csa3lxs is called to find values of an approximating cubic spline at specified three-dimensional coordinates. you call c_csa3lxs if you want to weight the input data values, calculate derivatives, or handle data sparse areas specially. if you do not want to do any of these three things, then use c_csa3ls instead. (yes she has a chill sister, we love her too 🫶)

c_csa3lxs 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_csa3lxs(n, x, y, z, u, wts, knots, smth, nderiv,
                no, xo, yo, zo, &ier);

then out[i] is the approximated function value at coordinate point (xo[i], yo[i], zo[i]) for 0 <= i < no. the space for out is allocated internal to c_csa3lxs and is no floats in size. she allocates her own space, she's independent like that. main character energy fr fr 🔥

⭐ heads up: the memory for out comes from inside c_csa3lxs, and it's no floats big. don't forget it exists, and don't be shocked when it does.

🌈 ACCESS 🌈

to use c_csa3lxs, load the NCAR Graphics library ngmath. that's it, that's the vibe check, you gotta link the library. 💅

🦋 SEE ALSO 🦋

• csagrid
• c_csa3s
• c_csa3xs
• c_csa3lxs

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. yes, it's a whole legal moment, respect it. 🌸

and that's the whole page, bestie!! this was c_csa3lxs(3NCARG) from the NCAR GRAPHICS manual, dated January 1999, and it lives in the UNIX section of the man pages. thanks for reading, you ate that 💖✨🎀🦋