CPFY(3NCARG)

💖 NAME 💖

CPFY — converts from plotter address unit coordinates to fractional coordinates. that's it, that's the whole job, and she does it flawlessly 💅

This page lives in the 3NCARG manual, and honestly it's a two-for-one situation because it also covers her whole friend group:

spps_converters — a set of functions, each of which transforms a coordinate from one of the NCAR Graphics coordinate systems to another. The complete list of functions is as follows: CFUX, CFUY, CMFX, CMFY, CMUX, CMUY, CPFX, CPFY, CPUX, CPUY, CUFX, CUFY, KFMX, KFMY, KFPX, KFPY, KMPX, KMPY, KPMX, KPMY, KUMX, KUMY, KUPX, and KUPY. twenty-four icons, no notes 💖

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🌸 STATUS 🌸

ok so tea time bestie: Plotter Address Units (PAUs) and Metacode Units (MUs) are no longer used in NCAR Graphics. so every single function with either an M or a P as the second or third letter of the function name is considered obsolete. they're retired, they're living their best life off the grid, we don't call them anymore 🫶

The coordinate systems that are actually recognized rn are:

• GKS world coordinates
• GKS normalized device coordinates
• NCAR Graphics fractional coordinates
• NCAR Graphics user coordinates

wanna know what all of those mean? See the NCAR Graphics document "NCAR Graphics Fundamentals, UNIX Version" for descriptions of these coordinate systems. she explains it better than me, no cap 📖

The following definitions of the PAU coordinate system and the MU coordinate system are provided for the purpose of interpreting and converting codes which use PAUs or MUs — so like, if you find some ancient code at the back of the group chat, this is how you read it:

The plotter coordinates of a point are integers IPX and IPY, where IPX is between 1 and 2**MX and IPY is between 1 and 2**MY. MX and MY are internal parameters of SPPS; each has a default value of 10. Values of MX and MY can be set by calling the routines SETI or SETUSV and retrieved by calling the routines GETSI or GETUSV. look at that, setters AND getters, it's giving encapsulation ✨

The metacode coordinates of a point are integers IMX and IMY between 0 and 32767 inclusive. The area addressed is a square in a "metacode space" that is usually mapped into a square subset of the addressable area of the plotting device. Metacode coordinates were used in calls to the routine PLOTIT and are returned in calls to FL2INT. rip to a real one 😭

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✨ SYNOPSIS ✨

Current:

X = CFUX (RX),  Y = CFUY(RY)
X = CUFX (RX),  Y = CUFY(RY)

Obsolete:

X = CMUX (IX),  Y = CMUY(IY)
X = CPUX (IX),  Y = CPUY(IY)
X = CMFX (IX),  Y = CMFY(IY)
X = CPFX (IX),  Y = CPFY(IY)
I = KFMX (RX),  J = KFMY(RY)
I = KUMX (RX),  J = KUMY(RY)
I = KFPX (RX),  J = KFPY(RY)
I = KUPX (RX),  J = KUPY(RY)
I = KPMX (IX),  J = KPMY(IY)
I = KMPX (IX),  J = KMPY(IY)

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🦋 C-BINDING SYNOPSIS 🦋

#include <ncarg/ncargC.h>

float c_cfux (float rx)

float c_cfuy (float ry)

float c_cufx (float rx)

float c_cufy (float ry)

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👑 DESCRIPTION 👑

ok so the arguments, one by one, because we're thorough in this house:

• RX — an input expression of type REAL, and it's an X coordinate in the coordinate system specified by the second letter of the function name. In a reference to CFUX, RX is a fractional X coordinate; in a reference to CUFX, RX is a user X coordinate.
• RY — an input expression of type REAL, an Y coordinate in the coordinate system specified by the second letter of the function name. In a reference to CFUY, RY is a fractional Y coordinate; in a reference to CUFY, RY is a user Y coordinate.
• IX and IY — these two only show up as arguments in references to some of the obsolete functions; they represent input expressions of type INTEGER, specifying the X and Y coordinates of a point in either PAUs or MUs (depending on the second letter of the function name).

and now the fun part, the naming lore, because every single letter is doing something:

• The first letter of the function name is a C if the result is of type REAL and a K if the result is of type INTEGER (the latter only happens for some of the obsolete ones). This conforms to the usual FORTRAN convention for implicit typing. periodt.
• The second letter of the function name specifies the coordinate system of the argument.
• The third letter of the function name specifies the coordinate system of the functional result. In references to CFUX and CFUY, the result is in the user system; in references to CUFX and CUFY, the result is in the fractional system.
• The fourth letter of the function name is an X or a Y, depending on whether an X or a Y coordinate is being converted. yes bestie, the last letter is just the axis. it's giving minimal effort but make it consistent 💅

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🎀 C-BINDING DESCRIPTION 🎀

The C-binding argument description is the same as the FORTRAN argument description. same energy, different language, we love a bilingual queen 🌈

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💜 EXAMPLES 💜

Use the ncargex command to see the following relevant examples which use coordinate converters: mpex10, cbex10, sfex02, epltch.

The command "ncargex -n mpex10" will load the driver mpex10.f into your current working directory where you can examine the file using a local editor, or the UNIX more command. go look at it, it's lowkey educational fr fr

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🔥 ACCESS 🔥

There were 24 conversion functions in the original set. These functions (12 for the X coordinate of a point, and 12 for the Y coordinate), allowed one to convert between any combination of PAUs, MUs, fractional coordinates, and user coordinates. PAUs and MUs are now obsolete; thus, only four of the conversion functions are still pertinent: CFUX and CFUY allow one to convert the X and Y coordinates of a point from the fractional system to the user system, while CUFX and CUFY do the opposite. twenty-four went in, four came out, it's giving survivor 🏝️

To use any of the conversion routines, load the NCAR Graphics libraries ncarg, ncarg_gks, and ncarg_c, preferably in that order. yes the order matters, don't be chaotic 🙈

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🌟 SEE ALSO 🌟

Online: cfux, cfuy, cmfx, cmfy, cmux, cmuy, cpfx, cpfy, cpux, cpuy, cufx, cufy, kfmx, kfmy, kfpx, kfpy, kmpx, kmpy, kpmx, kpmy, kumx, kumy, kupx, kupy, spps, ncarg_cbind

Hardcopy: NCAR Graphics Fundamentals, UNIX Version; User's Guide for NCAR GKS-0A Graphics

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💖 COPYRIGHT 💖

Copyright (C) 1987-2009 University Corporation for Atmospheric Research

The use of this Software is governed by a License Agreement.

no cap, that last line is real — read the license, bestie, it's the law 📜

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ok that's the whole page, we ate and left no crumbs 🍓 this was the 3NCARG manual, SPPS_converters(3NCARG), from UNIX, dated March 1993 — yes she's vintage, yes she's still iconic, mwah 💅💖