tedpop

Hello all. I am quite new to LabVIEW and am currently working on a Master's Thesis. This is the basic situation I am having. The program reads in a data file of various voltages in time series (an ECG recording) and then displays the contents to a waveform graph. However, i need to be able to have the user select a point on the graph, mark it, and then select another point, mark that too, and copy the data points in between. Unfortunately, i have no idea how to do this. An analogue to the UI would be ACID Pro 4.0, and audio mixing program, where the user selects the first downbeat of the mp3 file to begin the beat-mapping process from. Thanks.