Suppress Units in equatations

[hanneskoenig457]

What do you think of a function for suppressing units in an equation.

For example I have to do a transmission construction report for my studies.
Threrefore I need to calculate some factors which equatations contain of "unit" values. But the result should not contain of units, because i have to use them later in the script. The equatation at all should not contain units.

I created a workaround for me, but it´s not really intuitiv.
I hope you understand what I´m looking for.

What do you think?
Or did I overlook something

[Proektsoftbg]

Hi, @hanneskoenig457 !

I think it is generally not a good idea to use units and simply suppress their visibility. This is because units introduce hidden conversion factors in formulas that Calcpad resolves automatically.
So, if you have different units in the same equation and hide them, it will look ambiguous or simply wrong, for example:
With units:

a = 2m
b = 50cm
c = a + b' displays = 2m + 50cm = 2.50m

Without units:
c = a + b' displays = 2 + 50 = 2.50
This does not make any sence.

The other option is not to use units, but add them as text in comments. Also, you have to manually add the respective conversion factors in formulas:

a = 2'm
b = 50'cm
c = a + b*10^-2'm displays = 2 + 50*10^-2 = 2.50m

Probably this is the option you need. Most of our examples are created that way:
https://github.com/Proektsoftbg/Calcpad/tree/main/Examples

[Proektsoftbg]

I never had to suppress units so far. Can you please give me some example when this is needed. Maybe I can advice something.

[yuncu]

I also would like to supress units optionally. In my case, it is required when writing the selected rebar size, such as 20Ø16 (where 16mm is rebar diameter), or Ø16/15 (same rebar with 15cm spacing). Writing the units here does not look good.

[hildebrandopsj]

I never had to suppress units so far. Can you please give me some example when this is needed. Maybe I can advice something.

The correlation between tension and compression is given by fctm = 0,3*fck^2/3
with fck in MPa.

[Proektsoftbg]

@hildebrandopsj These formulas are empirical and there are plenty of them in Eurocode. In such cases, I compensate for the units directly in the formulas. For example:

f_ctm = 0.3*(f_ck/MPa)^(2/3)*MPa
k = 1 + sqrt(200mm/d) ' shear design as per EN 1992-1-1, § 6.2.2: k = 1 + sqrt(200/d)

... and so on, In general, whereever you meet the text 'where {some parameter} is in {some units}' substitute the units in the formula.
@yuncu In this case, you can use the @hildebrandopsj approach or #val / #equ as follows:

#val
'Selected reinforcement: Ø'Ø/mm'/'s/cm
#equ

Please, check the sample bellow:

[yuncu]

Thanks, both methods are OK for me.

[hanneskoenig457]

Here is my example:

and my workaound nearly like @hildebrandopsj said:

here without #hide:

I have to do addition with different Units , this is not possible. therefore I have to multiply the factors with "(factor)^-1" it works fine. But it´s a "workaround.

for me #val is no option because I need the result unitless. I could use your option with units only in comments like 10'm

but then I lose the nice feature of "auto unit detection", if i calculate later on with these values.

it´s just my idea, and for my example of equotation it would be nice. but the workaround works also. And it´s really few cases where it would be quite nice

[hanneskoenig457]

just because K_v should not contain a unit the same for K_2, K_1.
but F_Nt [kN];
v_w [m/s]
and b [mm]

I will try your @Proektsoftbg idea nevertheless. with snippets in Npp.
Thanks for advice

[hanneskoenig457]

but with your idea @Proektsoftbg you have the unit conversion e.g. *10^-2 in your Report except you use #val. but then you have to "code" the variable in to see the name in the report

[Proektsoftbg]

@hanneskoenig457 . I am not familiar with this formula. What I can see, is that most opearnds are unitless, including the result. Maybe there are also hidden units. It seems that v/100 is v/(100m/s). Please, check your design guidelines. So, maybe it is much simpler to write it as follows:

The other way looks more complicated than it should be. Then you can use the @hildebrandopsj trick but you will save some lines of code including the final conversion of K_v.

Or... you can even leave it like this and add an endnote that additional untis have been introduced to handle the units consistency. I would leave it to make my calculations easy to review and verify. This is the way to avoid errors, which is one of the main purposes of Calcpad.

[hildebrandopsj]

I think in another option, If you don't use these variables before this fórmula, you can define the variables unitless, and show unit with a simple text. This Will Guide the user to insert the correct value.

If you use the variables after, you can Just multiply then by the desired unit in a hide section