CSA2S(3NCARG)

💖 CSA2S — cubic spline approximation, simple entry for two-dimensional input, gridded output 💖

okay so bestie, welcome to CSA2S from the NCAR Graphics manual, section 3NCARG ✨ this is the chill, low-effort entrance to building a smooth cubic spline surface — 2D input data going in, a whole grid of output coming out. no cap. let's get into it 🦋

✨ SYNOPSIS ✨

CALL CSA2S (NI, XI, UI, KNOTS, NXO, ,NYO, XO, YO, UO, NWRK, WORK, IER)

(yes that's the call, verbatim, double comma and all, we don't touch the lore 💅)

🌸 DESCRIPTION 🌸

here's the whole cast of characters, one by one, no skips:

• NI — (integer, input) the number of input data points. it must be that NI .gt. 3, and depending on the size of KNOTS below, NI might have to be even bigger. so like, NI has a minimum, and also possibly a vibe-based higher minimum. 🙈
• 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, that is UI(L) is the value of the input function at the coordinate (XI(1,L),XI(2,L)) for L=1,NI. she's the data, she's the moment ✨
• KNOTS — (integer, input) the number of knots to be used in constructing the approximation spline. KNOTS is dimensioned for 2 and gives 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 clingy to your data 🎀
• NXO — (integer, input) the number of X coordinate values in the output grid.
• NYO — (integer, input) the number of Y coordinate values in the output grid.
• XO — (real, input) an array dimensioned for NXO containing the X coordinates of the output surface.
• YO — (real, input) an array dimensioned for NYO containing the Y coordinates of the output surface.
• UO — (real, output) an array dimensioned for NXO x NYO containing the calculated function values for the output surface. UO(I,J) is the calculated functional value at (XO(I),YO(J)) for I=1,NXO and J=1,NYO. this is the glow-up output, the grid reveal 🔥
• NWRK — (integer, input) the size of the WORK array. NWRK must be at least KNOTS(1)*KNOTS(2)*(KNOTS(1)*KNOTS(2)+3). do not skimp on this, she will not forgive you 😭
• 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, slay 💅. if IER is non-zero, then refer to the man page for csagrid_errors for details. (go read it, it's giving answers.)

💅 USAGE 💅

CSA2S is called to find an approximating cubic spline surface for two-dimensional input data. 🦋

but listen — if you want to weight the input data values, calculate derivatives, or handle data sparse areas specially, then you will need to use CSA2XS instead. CSA2S is the simple entry, CSA2XS is the one with extra settings. pick your fighter. 👑

🌈 ACCESS 🌈

to use CSA2S, load the NCAR Graphics library ngmath. that's it, that's the whole step 🫶

⭐ SEE ALSO ⭐

• csagrid
• csa2xs
• csa2ls
• csa2lxs

complete documentation for Csagrid is available at URL http://ngwww.ucar.edu/ngdoc/ng/ngmath/csagrid/csahome.html — go click around, it's iconic 📚

👑 COPYRIGHT 👑

Copyright (C) 2000 University Corporation for Atmospheric Research

the use of this Software is governed by a License Agreement. (read it, bestie, fr fr.)

and that's the whole page, main character energy from start to finish 💖 this was the UNIX version, dated January 1999, living in section 3NCARG as CSA2S(3NCARG) — mwah, periodt. 🌸✨🎀