KURVPD(3NCARG)

💖 KURVPD 💖

ok so this is KURVPD, a lil routine from the NCAR GRAPHICS manual (that's the 3NCARG vibe, bestie, that's literally where you found this page). It does interpolation and derivatives for closed parametric curves. Slay. ✨

🌸 NAME 🌸

KURVPD — nterpolation and derivatives for closed parametric curves

not me pointing out that the original says "nterpolation" and not "interpolation" — I'm keeping it fr fr because the rule is we don't change a single character. iconic behavior from 1998. 💅

🎀 SYNOPSIS 🎀

CALL KURVPD (T, XS, YS, XST, YST, XSTT, YSTT, N, X, Y, XP, YP, S, SIGMA)

So here's the tea 🫖: this subroutine behaves exactly like KURVP2 except that, on top of everything else, it also hands you back the first and second derivatives of the component functions in the parameterization. The interval [0.,1.] maps onto a closed curve in the plane. The resulting curve has a parametric representation where both of its components are splines under tension and are functions of the polygonal arc length.

⚠️ IMPORTANT: KURVP1 must be called before calling KURVPD. Like, no KURVP1, no KURVPD. it's giving prerequisite energy. 🙈

✨ DESCRIPTION ✨

• T — (real, input) A value to be mapped to a point on the curve. The interval [0.,1.] is mapped onto the curve such that 0. is mapped to (X(1),Y(1)) and 1. is mapped to (X(1),Y(1)). Any interval [TT,TT+1.] maps onto the entire closed curve. 🔁
• XS — (real, output) Contains the X coordinate of the point that T maps to. 💫
• YS — (real, output) Contains the Y coordinate of the point that T maps to. 💫
• XST — (real, output) Contains the first derivatives of the X component with respect to T.
• YST — (real, output) Contains the first derivatives of the Y component with respect to T.
• XSTT — (real, output) Contains the second derivatives of the X component with respect to T.
• YSTT — (real, output) Contains the second derivatives of the Y component with respect to T.
• N — (integer, input) The number of input data points. (N > 1) — so like, more than one, bestie, don't try it with one. 😭
• X — (real, input) An array containing the X values of the input points.
• Y — (real, input) An array containing the Y values of the input points. Adjacent pairs of points must be distinct. 🚨
• XP — (real, input) An array of length N as computed by KURVP1.
• YP — (real, input) An array of length N as computed by KURVP1.
• S — (real, input) An array of length N containing the polygonal arc lengths of the curve, as computed by KURVP1. 🧚
• SIGMA — (real, input) Tension factor. Values near zero result in a cubic spline; large values (e.g. 50) result in nearly a polygonal line. A typical value is 1. 🎚️

💜 ACCESS 💜

To use KURVPD, load the NCAR Graphics library ngmath. that's the whole access situation, no cap. 🫶

🌈 SEE ALSO 🌈

• kurvp1
• kurvp2
• fitgrid_params

Complete documentation for Fitgrid is available at URL http://ngwww.ucar.edu/ngdoc/ng/ngmath/fitgrid/fithome.html — go read it, it's giving ✨well documented✨.

👑 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 💖 that footer at the bottom said UNIX, dated March 1998, and yes it was literally signed KURVPD(3NCARG) — main character energy from the very last line. periodt. 💅✨