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Symbol Math and units in ...:=...=

ValeryOchkov
24-Ruby IV

Symbol Math and units in ...:=...=

Is it a bug?

Syb-A.png

7 REPLIES 7

In Mathcad 15 all OK!

Syb-A-15.png

The reason is that symbolic engine does not know what 'rad' or 'm' or any other unit is. Specifically, PTC Mathcad tries to symbolically sin(Pi*rad) and sees 'rad' as undefined symbol and not 1. This is same in Prime 2.0 and 15.0:

Untitled.png

When you use :=...= expression, defining Untitled.pngis the same as definig Untitled.png. Similarly, defining Untitled.pngis the same as definign Untitled.png.

The latter is where 15.0 and Prime 2.0 differ. To see advantage of Prime 2.0, consider:

Untitled.png

Bottom line: :=...= is _not_ just a convenience for displaying values, but it affects semantics (of symbolic evaluation).

Thanks, Jakov. I understand it.

But the questin was why all ok is in MC15 and not ok in Pime - see my pictures above.

Again dynamic units?

...:=...=... and ...:=... ...=... must be equal.

Valery Ochkov wrote:

Thanks, Jakov. I understand it.

But the questin was why all ok is in MC15 and not ok in Pime - see my pictures above.

Again dynamic units?

...:=...=... and ...:=... ...=... must be equal.

The difference is the adding of the (pseudo)unit rad. For numerics its just treated as a scalingfactor with the value 1, but to the symbolics its an unknown variable.

MC15 and Prime react in a different way on pseudounit deg (°). I am still unsure which behaviour has more logic, but unless we get full unit support in symbolics, too, we won't be perfectly happy anyway.

There is a switch in calculation options which promises something like units and constants in symbolic calculations, but it does not change anything. What is this option meant for?

BTW, I am missing Ctrl-Shift-P to get pi and why can't I use the degree sign ° from the keyboard in Prime as I am able to do in MC15?

14.09.png

14.09.png

See also

Fig-2-Triangle-Cose-Alpha.png

Took me a while, too.

14.09.png

Werner_E
24-Ruby V
(To:jkucan)

The latter is where 15.0 and Prime 2.0 differ. To see advantage of Prime 2.0, consider:

A minor advantage if you consider this:

14.09.png

compared to

14.09.png

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