CSA3LS(3NCARG)

💖 CSA3LS — cubic spline approximation, simple entry for three-dimensional input, list output 💖

okay bestie, welcome to the NCAR Graphics manual, section 3NCARG ✨ this is the page for CSA3LS and she is that girl — a cubic spline approximation, the simple entry version, for three-dimensional input, with list output. no cap. let's get into it 🫶

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✨ SYNOPSIS ✨

CALL CSA3LS (NI, XI, UI, KNOTS, NO, XO, YO, ZO, UO,
             NWRK, WORK, IER)

like, that's the whole vibe. one call and you're done 💅

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🎀 DESCRIPTION 🎀

here come the arguments, bestie, and every single one of them matters:

• NI — (integer, input) the number of input data points. she has to be NI .gt. 3, and depending on how big KNOTS is down below, NI might have to be even bigger than that. so don't come in with three points and expect magic 🙈
• XI — (real, input) an array holding the X - Y - Z coordinates of your input data points. it's dimensioned for 3 x NI. so XI(1,L) is the X coordinate, XI(2,L) is the Y coordinate, and XI(3,L) is the Z coordinate for the input domain, for L=1,NI. three rows, one for each axis, iconic layout 💜
• UI — (real, input) an array dimensioned for NI holding the function values at the input XI values. so UI(L) is the value of the input function at XI(L), for L=1,NI. she's the "what does the function actually equal here" girlie 🌸
• KNOTS — (integer, input) an array dimensioned for 3, holding the number of knots to use in each coordinate direction when constructing the approximation spline. KNOTS(I) must be at least 4 for I=1,3. and here's the tea: the larger the value of KNOTS, the closer the approximated curve comes to passing through the input function values. so bigger knots = more clingy, smaller knots = more chill 😌
• NO — (integer, input) the number of coordinate values in the output list. NO can be any positive number. any. positive. number. periodt 💅
• 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.
• ZO — (real, input) an array dimensioned for NO containing the Z 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),ZO(I)) for I=1,NO. this is the payoff, bestie, this is where she delivers 🎁
• NWRK — (integer, input) the size of the WORK array. NWRK must be at least NK * (NK+3) where NK = KNOTS(1) * KNOTS(2) * KNOTS(3). do the math before you call, fr fr 🧮
• WORK — (real, input) a work array dimensioned for NWRK. she's just there to do the heavy lifting behind the scenes 🫡
• IER — (integer, output) the error return value. if IER comes back as 0, then no errors were detected, slay. if IER is non-zero, then go read the man page for csagrid_errors for the details. don't ignore her, she's trying to tell you something 😭

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🌈 USAGE 🌈

you call CSA3LS to find an approximating cubic spline for three-dimensional input data. that's the whole job description 💼

but listen — if you want to weight the input data values, calculate derivatives, or handle data sparse areas specially, then this simple girlie is not enough and you will need to use CSA3LXS instead. she's the deluxe version 👑

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🔑 ACCESS 🔑

to use CSA3LS, load the NCAR Graphics library ngmath. that's it, that's the whole access situation 💖

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👀 SEE ALSO 👀

• csagrid
• csa3s
• csa3xs
• csa3lxs

and full complete documentation for Csagrid is available at this URL, copy it exactly bestie:

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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and that's the page, bestie!! this was the UNIX flavor of the CSA3LS(3NCARG) manual page, sourced from January 1999 — yeah she's an elder but she still ate 💅✨ go forth and spline responsibly 🦋