Executing "bring to center" on a free cursor in a log XY graph brings the cursor to the top rim of the graph (instead of the center)

[ghighuphu]

Dear support,

dear LV users,

selecting "bring to center" for a free cursor in a XY graph does not
bring the cursor into the center of the graph, but instead the command brings it to the
mean/average value. This is not an issue for a linear mapping
of the axis [due to the fact that the center of the axis is equal to
the middle/average value of the end points on the axis]. But when
mapping of the axis is logarithmic, the cursor ends up on the top of
the screen. That is because the average value of the end points
(min(y_axis)+max(y_axis))/2) is not equal to the center of the axis.

Is that a wished behavior, please?

Example: For an y_axis = [1..100], the awaited center position would be at
10 and not at 50.5. The center position for the logarithmic mapping
should be calculated as (log(min(y_axis))+log(max(y_axis)))/2, IMHO.

Kind regards,

[Richard20]

Hello,

which version of LabVIEW do you use?

Richard

[ghighuphu]

I am using LV 2013.01f please

[Richard20]

You are right, LabVIEW chooses this form (min(y_axis)+max(y_axis))/2).

You can go to "idea exchange".

Link:

http://forums.ni.com/t5/ideas/v2/ideaexchangepage/blog-id/labviewideas

here you can see how many people like your idea.

Perhaps it will be considered in the next version of LabVIEW.

[johnsold]

Richard,

Please check with R&D to see if they consider this a bug. While it is the built-in behavior, it clearly is meaningless, if not wrong, for the logarithmic mapping option.  If they classify it as a bug, then it does not need to go to the idea exchange.

Lynn

[Richard20 · Accepted solution]

Lynn,

it is definitly no bug. You can make a feature request.

I cannot escalate this case. LabVIEW wants this behaviour.

Perhaps it is possible to programm a work around with a property node.

Richard

[ghighuphu]

Dear Richard, dear Lynn

thank you for thinking about the issue.

What do you mean by "LabVIEW wants this behavior"?

Working with a property node is not really a useful workaround: the cursor is going to be updated only when the VI is running. I am working with the cursor only when debugging, that means the VI is mostly stopped, o running step-by-step.

OK, I'll post it as a feature request.

Cheers,

[ghighuphu]

Correction: the center on a log-axis is calculated differently:
y_visualCenter = 10^(log(min(y_axis))+log(max(y_axis)))/2

[ghighuphu]

posted as a feature request:
http://forums.ni.com/t5/LabVIEW-Idea-Exchange/Executing-quot-bring-to-center-quot-on-a-free-cursor-i...

[Richard20]

"LabVIEW wants this behaviour" means that the developer of NI programmed this function like this.

Sorry for my imprecise answer.