obtaining differnt values from graph to derivate

[tyl]

I am using Labview 7.0 and agilent 4194A. I need to obtain different values from the graph to derivate through the formula so as to find the resonance frequency. However, i am not able to obtain different points fromt he graph and hopefully i can get some help here. Thank you.

[smercurio_fc]

You really need to read the LabVIEW wiring guidelines. Your wiring is an absolute nightmare, making it close to impossible to understand what you're doing. You've got wires that are outputs looking like they're going into inputs. You've also got loops inside of loops - a sign of poor design. Plus, you've got the loop execution controlled by the values of signals. Also not a good approach.

I can't answer the question because I have no clue what you're trying to do based on trying to decipher the mess. As far as I could tell you have the array of values that you're graphing, and you're getting the min/max of that array. What else are you trying to get from this array of values? It also looks like you're getting some values from the instrument itself. Are you looking for the value at specific locations? Then the Index Array function is what you want, I guess.

[tyl]

the problem that i have with my programme is that the min and max array doesnt carry more than one information into the formulas for them to derivate. i need something to locate diferent points from the graph to derivate it in the while loop until i ind my min and max with is my resonance frequency.

[smercurio_fc]

The "Array Max & Min", by definition only return the maximum and minimum values of the array. These will always be just one value for each. You still haven't explained what information you're trying to get from the data. What does the data look like? Can you post an example graph? Based on what your formulas are doing (which I did not inspect) are you looking for peaks/valleys?

[tyl]

The many formulas there is to derivate the graph so that i am able to find my resonance frequency. and apparently, min and max array only gives one value which is not what i want. i need to obtain new values to loop the formula until i find that derivation = 0  so as to continue. 

[TreyB_NI]

I'm not entirely sure what you are trying to do in the grand scheme of your application, but it seems like you would like to detect several peaks of your waveform.  Take a look at the example advanced peak detector, which is located in our Example Finder (Help>>Find Examples), and browse to Analyzing and Processing Signals>>Signal Processing>>Advanced Peak Detector.vi.

Trey B
Applications Engineering
National Instruments

[Brian_Beal]

I have done this in Labview to find harmonics of the resonant frequency, but if you only want the resonant frequency, why not have the 4194A do it for you?