c_csa1s(3NCARG)

💖 c_csa1s — it's giving "cubic spline approximation" ✨

okay bestie, welcome to the NCAR GRAPHICS corner of the manual, page c_csa1s(3NCARG). this one is the simple entry for one-dimensional input, and she is lowkey iconic. 🎀

---

✨ NAME ✨

c_csa1s — cubic spline approximation, simple entry for one-dimensional input

like. that's the whole vibe. simple entry, one-dimensional, cubic spline approximation. periodt. 💅

---

🫶 FUNCTION PROTOTYPE 🫶

float *c_csa1s(int, float [], float [], int, int, float [], int *);

there she is. look at her. no cap, that pointer return is the main character. 👑

---

🌸 SYNOPSIS 🌸

float *c_csa1s(int n, float xi[], float yi[], int knots,
            int m, float xo[], int *ier);

---

💜 DESCRIPTION 💜

okay so here's the cast of characters, and you need to know every single one of them:

• n — (integer, input) the number of input data points. 🍓 heads up though: n has to be greater than 3, and depending on the size of knots below, n might have to be even bigger than that. so don't come in here with three points, bestie, she will not entertain it.
• xi — (real, input) an array dimensioned for n holding the abscissae for the input function. that's the x's. the whole x situation. ✨
• yi — (real, input) an array dimensioned for n holding the functional values of the input function — and listen, yi[k] is the functional value at xi[k] for k=0,n-1. they're matched, they're paired, they're soulmates. 💞
• knots — (integer, input) the number of knots used to construct the approximation spline. knots must be at least 4. and here's the tea: the larger the value for knots, the closer the approximated curve comes to passing through the input function values. more knots = more clingy = more accurate. 🦋
• m — (integer, input) the number of values to be calculated for the output curve. that's how many points of output she's serving you.
• xo — (real, input) an array dimensioned for m containing the X coordinates of the output curve. the glow-up coordinates, if you will. ✨
• ier — (pointer to integer, output) the error return value, aka the vibe check. if *ier comes back as 0, then no errors were detected — we ate and left no crumbs. 😌 if *ier is non-zero, then go refer to the error list in the error table for the details. that's your homework. 🔥

---

🌈 USAGE 🌈

you call c_csa1s to find an approximating cubic spline for one-dimensional input data. that's the mission, that's the assignment, that's the whole point.

BUT. important caveat bestie — if you wanna do any of these:

• weight the input data values
• calculate derivatives
• handle data sparse areas specially

then you're gonna need c_csa1xs instead. c_csa1s is the simple girlie; c_csa1xs is the deluxe edition. 💅

and what does c_csa1s give you back? she returns a pointer to a linear array of data that is the approximated curve. that's it, that's the gift. 🎁

---

🧚 ACCESS 🧚

to use c_csa1s, you need to load the NCAR Graphics library ngmath. that's the entry fee, no cap. 🔑

---

⭐ SEE ALSO ⭐

go check out her friends, they're all iconic:

• csagrid
• c_csa1xs
• c_csa1ls
• c_csa1lxs

and if you want the FULL documentation for Csagrid, it's available at this URL, copy it exactly bestie:

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.

like, legally. so read it. 🙈

---

and that's the whole page, bestie!! written under the UNIX manual name, from way back in January 1999, page c_csa1s(3NCARG) — she's vintage, she's iconic, she's still serving cubic splines to this day. mwah. 💖✨🎀