CSA1S(3NCARG)

💖 CSA1S — cubic spline approximation, simple entry for one-dimensional input 💖

okay bestie, gather round, because this one is from NCAR GRAPHICS (manual section 3NCARG, if you're keeping track) and it is literally the chill, low-effort entry point to approximating cubic splines in 1D. no cap. it's giving "I just want a smooth curve through my points and I don't wanna think about it" energy, and honestly? valid. 🦋

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✨ SYNOPSIS ✨

CALL CSA1S (NI, XI, YI, KNOTS, NO, XO, YO, NWRK, WORK, IER)

that's the whole vibe. one call, ten arguments, zero drama (unless IER says otherwise, but we'll get there 💀).

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🌸 DESCRIPTION 🌸

here's the tea on every single argument, no skipping, periodt:

• NI — (integer, input) the number of input data points you're feeding in. it must be that NI .gt. 3, and depending on how big KNOTS is (see below), NI may have to be even larger. so like… 3 points is not enough, bestie, don't try it. 🙈
• XI — (real, input) an array dimensioned for NI holding the X coordinates of your input data points.
• YI — (real, input) an array dimensioned for NI holding the function values at the input XI values. so YI(L) is the value of the input function at XI(L) for L=1,NI. yes, the L=1,NI thing, that's Fortran, we move. 💅
• KNOTS — (integer, input) how many knots go into building the approximation spline. KNOTS must be at least 4. and here's the glow-up: the larger KNOTS is, the closer the approximated curve comes to actually passing through the input function values. more knots = more clingy = more accurate. iconic behavior tbh. 👑
• NO — (integer, input) how many values you want calculated for the output curve.
• XO — (real, input) an array dimensioned for NO containing the X coordinates of the output curve.
• YO — (real, output) an array dimensioned for NO containing the calculated function values for the output curve. this is the payoff, the main character moment, the whole reason we're here. ⭐
• NWRK — (integer, input) the size of the WORK array. NWRK must be at least KNOTS*(KNOTS+3). do the math, don't skip it, it's not a suggestion. 😭
• WORK — (real, input) a work array dimensioned for NWRK. it's just the little backstage area where the spline gets ready. 🎀
• IER — (integer, output) the error return value. if IER comes back as 0, then no errors were detected — slay, we ate. if IER is non-zero, then refer to the man page for csagrid_errors for details. don't panic, just go read it. 💀

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🌈 USAGE 🌈

you call CSA1S to find an approximating cubic spline for one-dimensional input data. that's the whole job description. simple entry, simple life. ✨

but — and this is the important part, bestie — if you wanna weight the input data values, calculate derivatives, or handle data sparse areas specially, then CSA1S is not your girl and you need to use CSA1XS instead. different tool, different needs, no hard feelings. 🫶

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🔥 ACCESS 🔥

to use CSA1S, load the NCAR Graphics library ngmath. that's it. that's the access. go forth. 💜

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🦋 SEE ALSO 🦋

your reading list, bestie, go be literate:

• csagrid
• csa1xs
• csa1ls
• csa1lxs

complete documentation for Csagrid is available at this URL:

http://ngwww.ucar.edu/ngdoc/ng/ngmath/csagrid/csahome.html

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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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no cap, read the license, it's literally right there. 💅

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okay that's the whole page, you're officially a CSA1S girlie now, go make some beautiful smooth curves. this was CSA1S(3NCARG) from the UNIX manual, dated January 1999, and it still eats to this day. mwah. 💖✨🎀