floating point problem with ramp pattern

[Mal123]

I have problems with floating point in LAbVIEW.

Increasing A (A is defined in a range for convenience) I obtain different results on X.

This is probably due to floating point of START and END on Ramp pattern inputs.

How can I modify the diagram in order to obtain always the same (Right) result on X?

[altenbach · Accepted solution]

Your N is not an integer and you are also running into limitations of floating point math. 

A difference on the order of 1e-16 is not an error. DBL only gives you about 15 good decimal digits and errors accumulate with every operation.

[Mal123]

Thank you Altenbach, yes is not an error, but when I put this diagram inside my program I obtain strange results because varying A I have in some cases X=0 or X=39.4 and Ramp Pattern has in some cases Nsamples=0 or Nsamples=1.

Do you have some suggestions how can I do? Truncating values?

[altenbach]

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@Mal123 wrote:

Thank you Altenbach, yes is not an error, but when I put this diagram inside my program I obtain strange results because varying A I have in some cases X=0 or X=39.4 and Ramp Pattern has in some cases Nsamples=0 or Nsamples=1.

Do you have some suggestions how can I do? Truncating values?

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Well, a ramp with 0 or 1 samples is not a ramp. Make sure you have at least two points. What is a "strange result" can you be more descriptive?

Where are the inputs coming from and why are they so unreasonable?