(12-17-2021 04:49 PM)Thomas Okken Wrote:  You could write

C:300000_"km/s"

and then refer to it as C(), that is, a function call without passing arguments.

The only alternative, if you want to avoid the parentheses, would be to create a variable on the RPN side:

300000_km/s STO "C"

You could refer to that simply as C in your equations. It would be a variable, though, not a constant...

(12-16-2021 09:25 PM)Thomas Okken Wrote:  

(12-16-2021 09:00 PM)Ren Wrote:  What is the difference between Plus42 and Free42?

Everything you read in this thread!

Plus42 is an extended version of Free42, currently under development. It will feature all the capabilities of Free42, plus equations (modeled on those found in the HP-17B, 19B, 27S, etc., this is finished), attached units (modeled on those found in the HP-48/49/50 series; almost done), and directories for hierarchical storage of programs and variables, and support for larger display sizes, coming soon.

This will be a separate product, GPLv2 and free for Windows, MacOS, and Linux, and priced at something like €10 for Android and iOS. Price not yet decided, release probably in January or February.

(12-18-2021 05:04 PM)Thomas Okken Wrote:  New update:

1. Unit support in SOLVE
2. Unit support in INTEG

UPDATE:

Fixed two memory corruption bugs.

(12-18-2021 06:47 PM)Marco Polo Wrote:  Is it possible to define custom UOM like in 48?

(12-19-2021 07:00 AM)Thomas Okken Wrote:  Ah, I see. So a user-defined unit is simply a number with an attached unit, stored in a variable in a certain location? And the name of that variable then becomes the new unit?

That sounds straightforward enough. I'll add that functionality after I get directories working, it sounds like you'll want a separate directory to put those units and keep them from cluttering up your work areas.

(12-19-2021 11:11 AM)Thomas Okken Wrote:  My plan for name resolution is slightly more elaborate: search the current directory, and ancestors all the way to the root directory, but in addition, also a PATH directory where you can put symlinks to other directories, which will be searched from anywhere. So you don't have to clutter up the root directory with all the things that should be globally available.

(12-19-2021 11:11 AM)Thomas Okken Wrote:  My plan for name resolution is slightly more elaborate: search the current directory, and ancestors all the way to the root directory, but in addition, also a PATH directory where you can put symlinks to other directories, which will be searched from anywhere. So you don't have to clutter up the root directory with all the things that should be globally available.

(12-19-2021 12:56 PM)roberto_abraham Wrote:  1 R = 1/(4 pi) 10^10 photon sec^−1 m^−2 Sr^−1

I bet this turns out to be a tricky edge case, since it involves two somewhat special situations. While 'photon' is part of the definition, it's just a dimensionless pure number that doesn't reduce to an SI base unit and instead should get carried along in calculations but stay symbolic. On the other hand, the solid angle is dimensionless but transforms to other dimensionless solid angle measures that have different exponents (e.g. arcsec^-2).

(12-19-2021 01:36 PM)Marco Polo Wrote:  

(12-19-2021 11:11 AM)Thomas Okken Wrote:  My plan for name resolution is slightly more elaborate: search the current directory, and ancestors all the way to the root directory, but in addition, also a PATH directory where you can put symlinks to other directories, which will be searched from anywhere. So you don't have to clutter up the root directory with all the things that should be globally available.

It seems to me a very smart idea!

I think Plus42 is becoming something very near my "killer Calc" (the ideal would be a DM48, based on 48gx but without graphic)

(12-19-2021 03:46 PM)Vincent Weber Wrote:  

(12-19-2021 01:36 PM)Marco Polo Wrote:  It seems to me a very smart idea!

I think Plus42 is becoming something very near my "killer Calc" (the ideal would be a DM48, based on 48gx but without graphic)

Plus42 already is my killer calc, I always wanted a pocket programmable (not a monster like the 48) merging the powers of the 42S, some 41cx extensions (like X?NN), the 17B/27S solver, and the 35S extensions. For this last one, Plus42 already have the ability the use equations in programs, and vector/matrices litterals in equations. It will soon have constants. The only missing stuff I could think of would be fraction mode and one-line complex numbers entry, but I'm not sure there is a lot of demand for that. Also an ALG mode, but I think nobody is interested, this is a RPN kingdom

(12-19-2021 03:38 PM)Thomas Okken Wrote:  I don't know about the solid angle, though. The 48G has only the Steradian, which is a base unit and doesn't convert to anything else: 1_sr 1_r^2 CONVERT => Inconsistent Units.

(12-19-2021 08:04 PM)roberto_abraham Wrote:  Being dimensionless, solid angles seem to pose significant challenges for unit conversion routines.

(12-19-2021 09:18 PM)Thomas Okken Wrote:  Not that it couldn't be. Mathematically speaking, one steradian is one square radian... But if there are undesirable side effects to changing the definition of sr from base unit to r^2, another option would be to simply add appropriate definitions for square degree, square arcminute, etc., based on the steradian.