CPFX(3NCARG)

✨ NAME ✨

CPFX — bestie, this one converts from plotter address unit coordinates to fractional coordinates. That's the whole job. That's the vibe. 🎀

And because the pages travel in packs, this one also carries the scoop on spps_converters — a whole girl gang 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 of them. Icons only. 👑

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🦋 STATUS 🦋

Okay so here's the tea, and it's a little sad: Plotter Address Units (PAUs) and Metacode Units (MUs) are no longer used in NCAR Graphics. So literally every function with either an M or a P as the second or third letter of the function name is considered obsolete. RIP to them, they served. 💀

The coordinate systems that are actually recognized right now are:

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

Wanna know what all of those mean? Go read the NCAR Graphics document "NCAR Graphics Fundamentals, UNIX Version" — it has descriptions of every one of these coordinate systems. 📚

Now, because old code still exists and we are nothing if not generous, 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:

• 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. ✨
• 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. 🫶

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🌸 SYNOPSIS 🌸

Current: (the ones that still eat 💅)

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

Obsolete: (retired but not forgotten, we still love them 😭)

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 🧚

For my C girls and theys, here's the include and the four current faves:

#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 💖

Okay so the arguments, let's decode them like we're reading a group chat:

• 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. So in a reference to CFUX, RX is a fractional X coordinate; in a reference to CUFX, RX is a user X coordinate. Same letter, different universe. 🌀
• RY — an input expression of type REAL, and it's a 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 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 function names are literally a little code, and it's giving ✨cryptic but make it FORTRAN✨:

• 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. No cap.
• 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. So CFU* goes fractional ➡️ user, and CUF* goes user ➡️ fractional. Two-way street, iconic behavior. 🛣️
• 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. Simple as. 💫

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🎀 C-BINDING DESCRIPTION 🎀

The C-binding argument description is the same as the FORTRAN argument description. Copy-paste energy, but make it intentional. 🫶

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🌈 EXAMPLES 🌈

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

And the glow-up move:

ncargex -n mpex10

That command 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 bestie, it's right there. 👀

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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. Every combo. Full matrix. Slay. 💅

But PAUs and MUs are now obsolete, so 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.
• CUFX and CUFY do the opposite. 🔁

To use any of the conversion routines, load the NCAR Graphics libraries ncarg, ncarg_gks, and ncarg_c, preferably in that order. Order matters, bestie. Don't be chaotic about it. ⭐

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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.

Yes, the license is real and you should read it. Not me being dramatic, that's just the rules. 🙈

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Okay that's the whole page, bestie — CPFX and its SPPS_converters fam, straight from the UNIX manual, March 1993 edition. Go convert some coordinates. You got this. 💖✨🎀🦋