dot product vs star symbol ? - Printable Version

dot product vs star symbol ? - Printable Version

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dot product vs star symbol ? - dg1969 - 05-15-2015 05:16 PM

An investigation was conducted a long time ago ...

Can we hope to get a nice "dot" (Latex look) instead of the "star" ?

RE: dot product vs star symbol ? - Helge Gabert - 05-15-2015 05:35 PM

Some people (myself included) prefer the star for the multiplication symbol. Dots are too similar to decimal points, and can be confusing to the eye.

But it would be OK to make that available as a setup option, so the user can choose.

RE: dot product vs star symbol ? - Eddie W. Shore - 05-15-2015 07:29 PM

This sounds like a reasonable feature for the user to choose, as long as the two symbols don't conflict when programs are transferred between users.

RE: dot product vs star symbol ? - petaks01 - 05-15-2015 07:33 PM

I wouldn't mind to have the "x" as selectable symbol.

RE: dot product vs star symbol ? - dg1969 - 05-15-2015 08:01 PM

(05-15-2015 05:35 PM)Helge Gabert Wrote: But it would be OK to make that available as a setup option, so the user can choose.

I agree with you it will be the best solution. I have of course no idea of the difficulties to be overcome for this to work. The problems associated with the digit grouping is an illustration. I wonder if there is a connection between these two aspects ? When a solution will exists to generalize digit grouping (Home and CAS side) maybe the possibility to choose between "point" and "star" will also be offered ? I hope.

For me, even on a screen like de prime \( \dfrac{a \cdot \sin(x \cdot y)}{b \cdot A} \) is more readable than \( \dfrac{a * \sin(x * y)}{b * A} \) for me it's not just more beautiful it's really more readable... with long mathematical expressions I have a more immediate overview . This "*" give more painful reading, the expression is also less compact.
Have you ever seen a scientific book make use of this "*" ? Compliance with the typographic rules give much more enjoyable reading . Text written with MSWord vs Latex for example.
Although the screen of the prime is not as good as our smartphone I think he is good enough to support that type of improvement.

RE: dot product vs star symbol ? - salvomic - 05-15-2015 08:05 PM

(05-15-2015 08:01 PM)dg1969 Wrote: For me, even on a screen like de prime \( \dfrac{a \cdot \sin(x \cdot y)}{b \cdot A} \) is more readable than \( \dfrac{a * \sin(x * y)}{b * A} \) for me it's not just more beautiful it's really more readable... with long mathematical expressions I have a more immediate overview . This "*" give more painful reading, the expression is also less compact...

I agree. It's more readable and also like in the Math's books...
Then * remember to me something of abstract algebra, instead :-)

Salvo

RE: dot product vs star symbol ? - dg1969 - 05-15-2015 08:13 PM

(05-15-2015 08:05 PM)salvomic Wrote: Then * remember to me something of abstract algebra, instead :-)

Salvo

Primo, these '*' reminds me the mechanical typewriter when there was not much choice among characters, secundo it is for me the convolution product symbol...

RE: dot product vs star symbol ? - salvomic - 05-15-2015 08:21 PM

(05-15-2015 08:13 PM)dg1969 Wrote: Primo, these '*' reminds me the mechanical typewriter when there was not much choice among characters, secundo it is for me the convolution product symbol...

also, also! yes!
:-)

RE: dot product vs star symbol ? - Helge Gabert - 05-16-2015 02:22 AM

Well, to each his or her own!

a⋅sin(x⋅y)/(b⋅.5) is not more readable than a∗sin(x∗y)/(b∗.5) -- at least, to my eyes.

Let the user choose through the setup menu!

RE: dot product vs star symbol ? - Joe Horn - 05-16-2015 05:05 AM

I was going to recommend the Unicode "multiply" symbol [×], which is already what's on the keyboard's multiply key .... but then I tried it in the Prime font, and it looks too much like the letter "x" (unlike in TeX):

[Image: times.png]

Unfortunately, I grew up thinking in BASIC, so using an asterisk for multiplication doesn't bother me at all.

Have you noticed that 2**3 performs 2^3 in CAS? Traumatic memories of FORTRAN arise. But I digress.

RE: dot product vs star symbol ? - parisse - 05-16-2015 06:13 AM

(05-16-2015 05:05 AM)Joe Horn Wrote: Have you noticed that 2**3 performs 2^3 in CAS? Traumatic memories of FORTRAN arise. But I digress.

I never programmed in fortran, but I find ** sometimes useful, if you are on a new custom keyboard for example. Moreover typing twice * is sometimes not longer than typing ^. And ** is still useful in more modern programming language, like Python for example...

RE: dot product vs star symbol ? - Joe Horn - 05-16-2015 09:30 AM

Here's how the available cross and dot symbols in Prime's current built-in font would look on the actual Prime display (in Large Font size), with pixel accuracy for both the characters and the spacing:

[Image: times2.png]

The first two crosses (D7 and 2715) look identical, but the latter is actually slightly larger. The dots look nice... but what about when mixed with numbers containing decimal points? That'll be another Photoshop project for another day.

RE: dot product vs star symbol ? - petaks01 - 05-16-2015 10:10 AM

Thanks Joe!

30FB looked really nice and is easy to read since the spacing makes it different from the decimal point. D7 is what I have been using on paper the last 40 years and it is really hard to change that old habit but I am willing to try if the option is available on the Prime some day Wink

RE: dot product vs star symbol ? - salvomic - 05-16-2015 10:22 AM

yes, ok...
but, rigorously speaking, "dot" and "times" are used also for "dot product" and "vectorial product" (this one also with "wedge" \( \wedge \), sometimes)...
gradient \( \nabla \vec{v} \)
divergence \( \nabla\cdot \vec{v} \)
curl \( \nabla\times \vec{v} \)
dot product \( \vec{u}\cdot\vec{v} \)
vectorial product \( \vec{u}\times\vec{v} \) (or \( \vec{u}\wedge\vec{v} \))
That said, I think that something like "times" (\(\times\)) (or also "dot" (\(\cdot\))) is better than the star *, for multiplication Smile

RE: dot product vs star symbol ? - dg1969 - 05-16-2015 09:16 PM

(05-16-2015 09:30 AM)Joe Horn Wrote:

My wish : the #30FBh but with less space... so #30FBh but with the space of #22C5h or #B7h picture...

Thank's for theses pictures

RE: dot product vs star symbol ? - Ollie - 05-16-2015 09:37 PM

Yes please, this NEEDS to be a feature.
Also why can't we have the multiplication symbol removed when there's a coefficient in front of a variable? "2x instead of 2*x"
This would also increase readability.

RE: dot product vs star symbol ? - Mark Hardman - 05-16-2015 09:52 PM

(05-16-2015 09:30 AM)Joe Horn Wrote: Here's how the available cross and dot symbols in Prime's current built-in font would look on the actual Prime display (in Large Font size), with pixel accuracy for both the characters and the spacing:

The first two crosses (D7 and 2715) look identical, but the latter is actually slightly larger. The dots look nice... but what about when mixed with numbers containing decimal points? That'll be another Photoshop project for another day.

I see another bolder looking dot at #2022h (alt+8226):

[attachment=2031]

That one definitely cannot be confused with a decimal point/separator.

RE: dot product vs star symbol ? - Joe Horn - 05-17-2015 03:19 AM

(05-16-2015 09:37 PM)Ollie Wrote: Also why can't we have the multiplication symbol removed when there's a coefficient in front of a variable? "2x instead of 2*x"
This would also increase readability.

That's problematic if there's more than one variable. 2*x*y can't be displayed as 2xy, because 'xy' is ambiguous (is it x*y or is it a variable called 'xy'?). 2x*y? Yuck.

(05-16-2015 09:52 PM)Mark Hardman Wrote: I see another bolder looking dot at #2022h (alt+8226)... That one definitely cannot be confused with a decimal point/separator.

I intentionally omitted that one because it's the "bullet" character [•], too big for a multiplication symbol. 25CF [●], the "black circle" character, would be even more annoying. IMHO.

RE: dot product vs star symbol ? - Spybot - 05-17-2015 04:42 AM

Thanks Joe!

I personally like the #22C5h option, because it looks nice, it is easy to read, neat, it doesn't take too much space and it is not too boldy. (I'm not sure it'll be suitable for every situation though).
I agree that it would be a nice feature to implement on the Prime, star doesn't look nice in fact it is kind of distracting and make the reading more difficult.
Remembering old times with HP generation 4 calculators, they used to handle the star too, but only in editing mode. then the results sometimes looked weird.

[attachment=2045] [attachment=2046]

That's why I think it maybe difficult to decide which character would be the more appropriate to represent the multiplication symbol on the HP Prime.