As far as I know though it rounds off the figure itself it does not actually make the artboard a different size.
I know that bugs you and probably most people but I think ID does this as well and it still works for everyone.
This might actually have something to do with a legal matter rather than a technical. It might be someone or some other developer has a patent on that kid of display of dimensions. As certain dimensions in Illustrator can be displayed in 3 decimal places.
I think Quark Express can display this in perhaps four such places and they may actually have the patent and so if you don't make arrangements you go to court and arrangemens might not be in the offering at that.
Well I seem to recall one of the developers has a priority holding on the technology to display in such way for page sizes and perhas other dimensions as well.
Perhaps I am off base but i think that is the issue and that your document will actually be the size you speciaiy.
I know this seems like some that should not be.
I am certain if I am wrong someone will let us know.
All values in an Illustrator file are stored as points. When you enter a size of 1˝, Illustrator converts that to 72 points and that is the value stored. When you ask for the size the points are converted back to inches (or centimetres or millimetres or picas or whatever "Ha" means).
1.625˝ is 117 points, and you can trust that that is the value Illustrator remembers. When you ask for inches, Illustrator only shows precision up to 1⁄100 of an inch, but that doesn’t mean that the size is off. The 117 points saved in the file is 1.625˝.
Thank you very much for your explanation. You would think that would be in "the book" somewhere. I'm working my way thru "Real World Illustrator CS4" and "Illustrator CS4 Wow! Book". Any other suggested reading or instruction I should consider?
Here is the response I got from Adobe Tech Support which is also helpful information...
Based on your email, I understand that you are not able to set the
artboadr size 1.625" x 1.417", but can set the size as 1.63" x 1.42.
I value the importance of your concern and I am here to assist you.
I would like to inform you that I have researched on the issue on my
system and found that it can be done in Illustrator CS4.
For that, please follow the steps given below:
1.Open the Artboard Options dialog box by double-clicking the Artboard
tool , or clicking the Artboard tool and then clicking Artboard Options
button in the Control panel.
2.In "Width and Height" column you can put your desired size in inches,
it converts it to px. I have checked, it takes the value upto 0.0001" .
I believe, this answers your query.
I don't understand why this works this way. 1/8 inch is a standard measurement in the print industry, and to have no real way of precisely measuring to that degree is absolutely insane to me. I do not like taking things on faith when it comes to formatting for printing (which is what Illustrator's main use is for many of us) - printing is expensive and time consuming, and things need to be precise. It's not asking anything crazy to be able to enter ".125in" for a width or height of something. This is also an issue in the "align" panel. When trying to set spacing between two objects, ".125" becomes ".13." This is unacceptable and should be remedied.
as mentioned in previous posts, 0.13 is the value shown due to rounding, your actual value is still 0.125
But...I don't understand why? Why not just show the value if that is the value?
I don't know, usually when designing the UI one has to decide how to make all elements "look" good, and when it comes to decimal places one needs to pick a number, it's usually rounded to 2 or 3 decimals, since the actual number could go to infinity.
When designing the UI (I am actually a User Interface and User Experience Designer first, print designer second), you don't just make decisions to make things pretty by arbitrarily "picking a number". They must both look good and solve the problem. Now of course, you don't want infinite decimal points - but you must address common use cases. 1/8" measurements are an exceedingly common use case (being the most common bleed measurement for one thing, so common the grid in Illustrator defaults to eighths), so 3 decimals would be, to me, the only reasonable choice (4 decimal points would be ideal in a vacuum, since 16ths are pretty common measurements, but I understand the limitations from converting points to inches requires no more than 3 decimal places).