Issues with ZERO on SetVariable Controls

My guess is that you're running into floating point precision errors, depending on what N is and what your increment is. See https://www.itu.dk/~sestoft/bachelor/IEEE754_article.pdf for full details

OK. I would think that a range -2 to 2 with increments 0.1 would not have this problem. Here is the setvariable control extracted from the panel. The value _should_ be exactly zero. It increments up/down to exact values above/below 0.1 or -0.1 with no issues.

Here is the value with a format code in the panel display. The value shows 0.0 but is not set at zero exactly.

Here is the statement with an increment at 0.1.

When I update to 0 manually, the value is _NUM:0 (exactly).

The precision offset is not critical in my calculations. But it could be for someone. Should there be a standard way to avoid this? Something akin to a checkbox: [  ] round number values to format precision.

Igor Pro 7.08 on macOS 10.13.6

0.1 has no exact representation in ANY IEEE floating point format: it is a repeating bicimal:

https://www.exploringbinary.com/why-0-point-1-does-not-exist-in-floatin…

You should never use an increment like this and expect to get exactly 0 after repeated increments and decrements.

Use rounding before using the value:

Well! I learned something that I probably did know vaguely but never really had hit home properly.

I have a feature request in the works.