find difference of values and slopes for a specified interval in X coordinates

[KevinKM]

Hi all,
Suppose i have a sine wave of 100hz freq with sampling freq of 1000hz. I want to plot two points on a X-axis and i want to find difference of corresponding y values and display it in the front panel. How do i go about finding the slope for the same. Any help would be appreciated.

[P@Anand]

What do you mean plotting two points? You have the linear fit vi using that you can find the slope.

[mikeporter]

If you have the plot I will assume that you have arrays of X and Y values. For each of the X values:

1. Use the Threshold 1D Array function with the array of X values as the array input and your target X value as the scalar input. The output is a fractional index of where that X value falls in the array of X values.

2. Use the Interpolate 1D Array function with the array of Y values as the array input and the fractional index from the threshold operation as the index input. The result is the interpolated Y value at the specified fractional index.

Mike...