CSA2LXS(3NCARG)

💖 CSA2LXS 💖

okay bestie, gather round, because we're about to talk about CSA2LXS — a real one from the NCAR GRAPHICS family, sitting pretty in section 3NCARG of the manual. it's giving "cubic spline approximation, expanded entry for two-dimensional input, list output" and honestly? she ate. 🎀

✨ NAME ✨

CSA2LXS — cubic spline approximation, expanded entry for two-dimensional input, list output. 💅

🌸 SYNOPSIS 🌸

CALL CSA2LXS (NI, XI, UI, WTS, KNOTS, SMTH, NDERIV,
              NO, XO, YO, UO, NWRK, WORK, IER)

🦋 DESCRIPTION 🦋

okay so here's the whole cast of characters, one by one, no skips, no skimming, we're doing this properly:

• NI — (integer, input) the number of input data points. and listen, there's a rule: it must be that NI .gt. 3, and depending on the size of KNOTS below, NI might have to be even bigger. so don't try to be cute with it. 🙈
• XI — (real, input) an array holding the X - Y coordinates of the input data points. XI is dimensioned for 2 x NI. XI(1,L) is the X coordinate and XI(2,L) is the Y coordinate for the input domain, for L=1,NI.
• UI — (real, input) an array dimensioned for NI containing function values at the input XI values. so UI(L) is the value of the input function at the coordinate (XI(1,L),XI(2,L)) for L=1,NI.
• WTS — (real, input) an array dimensioned for NI containing weights for the UI values at the input XI values. that means WTS(L) is a weight for the value of UI(L) for L=1,NI. if you do not want to weight the input UI values, then set WTS(1) to -1. the weights in the WTS array are relative and may be set to any non-negative value. when CSA2LXS is called, the weights are summed and the individual weights are normalized so that the weight sum is unity. normalization era. ⚖️✨
• KNOTS — (integer, input) the number of knots to be used in constructing the approximation spline. KNOTS is dimensioned for 2 and provides the number of knots to be used in the X and the Y directions. both KNOTS(1) and KNOTS(2) must be at least 4. the larger the values for KNOTS, the closer the approximated curve will come to passing through the input function values. more knots = more snuggle with your data, basically. 🪢
• 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.
• NDERIV — (integer, input) an array dimensioned for 2 that specifies, for each coordinate, whether you want functional values (=0), first derivative values (=1), or second derivative values (=2). pick your fighter. 👑
• NO — (integer, input) the number of coordinate values in the output list. NO can be any positive number.
• XO — (real, input) an array dimensioned for NO containing the X coordinates of the output list.
• YO — (real, input) an array dimensioned for NO containing the Y coordinates of the output list.
• UO — (real, output) an array dimensioned for NO containing the calculated function values for the output spline. UO(I) is the calculated functional value at (XO(I),YO(I)) for I=1,NO. this is the payoff, bestie. 🌟
• NWRK — (integer, input) the size of the WORK array. NWRK must be at least KNOTS(1)*KNOTS(2)*(KNOTS(1)*KNOTS(2)+3). yes that's a real formula, no you cannot vibe your way around it. 💀
• WORK — (real, input) a work array dimensioned for NWRK.
• IER — (integer, output) an error return value. if IER is returned as 0, then no errors were detected. if IER is non-zero, then refer to the man page for csagrid_errors for details. 👀

🫶 USAGE 🫶

CSA2LXS is called 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 CSA2LS instead. know the difference, it's important. 💜

🌈 ACCESS 🌈

to use CSA2LXS, load the NCAR Graphics library ngmath.

⭐ SEE ALSO ⭐

• csagrid
• csa2s
• csa2xs
• csa2ls

complete documentation for Csagrid is available at URL http://ngwww.ucar.edu/ngdoc/ng/ngmath/csagrid/csahome.html

👑 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 — every last detail, nothing dropped, we keep it thorough around here. 🧚 this was the UNIX version of CSA2LXS(3NCARG), dated January 1999, and it's still serving looks. mwah. 💋🎀