How can I plot Error Bars with Diadem

[Engbrecht]

I have a set of data in which both the x data and/or the y data have an associate error range that I would like to plot. Virtually every data analysis package I have ever seen makes this trivial. However, Diadem and Labview do not seem to be able to do this rather basic function. Is it just me or is this a major oversight on the part of National Instruments.

[Brad_Turpin]

Hi Engbrecht,

Vertical error bars are pretty easy to create in DIAdem, but horizontal error bars, though still achievable, are more of a manual chore. In both cases you need to create a new channel for both the Y- and Y+ values as well as the X- and X+ values. For vertical error bars you just need to select the graph type "Differential bars", then configure its display to be "Range" mode instead of "Bars" mode. For horizontal error bars you need to create a separate curve each for the left vertical bar, the right vertical bar and the horizontal connecting line. This horizontal connecting line can only be a constant width across the whole graph, so it can not automatically span the distance between the left and right vertical lines of
the horizontal error bar for each point.

Here's an example of a graph with both vertical error bars (easy) and horizontal error bars (quite manual). This particular example shows error bars in both directions of +/- 5% of the point's amplitude, but you could use a constant value or configure point-specific values for the error bars in either direction.

The 5% deviations in the X-, X+, Y-, and Y+ channels used by the error bars were created from the original channels with the following simple commands in the Formula Calculator:

Ch('Frequency-'):= Frequency*0.95
Ch('Frequency+'):= Frequency*1.05
Ch('Af-'):= Af*0.95
Ch('Af+'):= Af*1.05

Ask if you have further questions,
Brad Turpin
NI

[sado]

Hello All,

I have 2 data samples w/ 2 different time stamps.  one set of data is sampled every hour and the other set of data is collected every 5 min.  I need to plot the two data to see the correlation b/t them, which mean i must have the same interval for the time (or time stamp).  How do i add/remove data sampled points from a particular channel/table?  Can i write a VB script that will do this quickly for a large amount of data?     

thanx,

Sa Do, EIT

[Brad_Turpin]

Hi sado,

Actually DIAdem has a function to do just this, it is called "Linear Mapping" and can be found in the "Curve Fitting" ANALYSIS palette.  On the topic of vertical and horizontal error bars, as of DIAdem 10.1 there is finally full coverage in DIAdem for a wide range of x and y error bar choices-- this is now a first class citizen feature.

Brad Turpin
DIAdem Product Support Engineer
National Instruments

[James M]

Hi Sado,

Brad is correct, however; if you are plotting waveforms (or data with relative timestamps), DIAdem will automatically plot the graphs correctly without having to manually interpolate using linear mapping.

Regards,