Compare timestamps from waveform will not work

[Tanchris]

Hi,

I try to search for a special timestamp in an array of timestamps (created from a waveform of a daqmx-data-acquisition).

But the precision of the timestamp is too high and the timestamp never match (att. file).

I`ve tried to change the microseconds to 3 decimal digits, but it will not work.

Two questions to this topic:

1. is it possible, that I got directly from daqmx a waveform with only 3 decimal (and after that only "0")

2. how can I change the incoming timestamp to 3 decimal (I´ve tried to convert in a string and then back with "%<%x %.3X>T" --> but no effect)

Thanks for your help.

[GerdW · Accepted solution]

Hi Tanchris,

generic rule: NEVER compare float numbers for equality!

Better approach: search the minimum for abs(TimestampArray - Timestamp):

[Tanchris]

That works...yeah... Thanks a lot GerdW.

Do you know, is there also a way, to cut the timestamp before I compare it or has a timestamp ever its highest solution?

[GerdW]

Hi Tanchris,

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@Tanchris wrote:

Do you know, is there also a way, to cut the timestamp before I compare it or has a timestamp ever its highest solution?

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A timestamp is a timestamp. It consists of 128 bits, with 64 bits counting seconds since epoch and 64 bits for fractions of a second. You may fiddle with the timestamp value (using DateTimeToSeconds and SecondsToDateTime just to change the fraction part), but why?

Measurement data should be kept in full resolution, you can handle anything in post-processing…

[Tanchris]

Thats right and I´ll do it with your snippit...

Have a nice day...thanks for support...