What is the correct way to write this iLogic code / Parameter equation?

[chris]

I want to round up a dimension, based on another dimension to the nearest 1/8".

Examples:

if d17 0.735, then I want d18 to = 0.75

if d21 = 0.317 then I want d22 to = 0.375

can you show this for both iLogic and for Parameters?

[Andrii_Humeniuk]

Hi @chris . I recommend trying the mathematical iLogic snippet "Round Closest to Increment".

inc = .125 ' rounding increment ( .125, .25, .5, etc)
roundedClosest = Round(Round(d0,4) / inc) * inc

Example formula for parameters:

round(d0 / 0,125 mm) * 0,125 mm

[chris]

@Andrii_Humeniuk  I think your example shows how to round a single dimension, but I am looking for one dimension to be rounded "up" based on a reference dimension... unless I'm missing something...?

[Andrii_Humeniuk · Accepted solution]

You need to use the math function Ceil

For iLogic:

inc = .125 ' rounding increment ( .125, .25, .5, etc)
roundedClosest = Ceil(d0/inc) * inc

For Parameters:

Ceil(d0 / 0,125 mm) * 0,125 mm

[marcin_otręba · Accepted solution]

There is no need to use ilogic , you can just use formula in parameters as @Andrii_Humeniuk wrote:

Ceil(d0 / 0,125 mm) * 0,125 mm

it will round it up as you wanted.

but f you want to use formula in ilogic then it would look like:

Parameter("d18") = (Ceil(d17 / 0.125) * 0.125)
Parameter("d22") = (Ceil(d21 / 0.125) * 0.125)
iLogicVb.UpdateWhenDone = True

here is help reference:

Inventor 2025 Help | Math Functions Reference (iLogic) | Autodesk