LabVIEW
Comparing array elements value In labview
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To determine the difference between consecutive elements of a loop, you can auto-index your array with a 0 initialized shift register, and wire teh element to the right side whilst calculating the difference.
The Absolute value function will allow you to find the magnitude of the difference.
How are you deciding between Ch1 and Ch2? When you say "sending Boolean true signal 3 times" do you mean 3 digital high value pulses? You can send boolean pulses with the digital waveform nodes:
Here I send 3 samples with Toggle - this alternates the signal. By default, the values are 0 and 1, so this means the output will be 0,1,0. The sample rate determines the rate of the waveform that is outputted whilst the number of signals determines the number of digital outputs you intend to use.
Ah - let me explain a little more clearly. I used 3 samples to send 1 pulse from low to high to low. If you want 3 pulses, and to end on low, you should wire a 7 to the input where I wired 3. This will give 3 high and 4 low values, or 3 pulses ending low.
Do you see what I mean?
@cbutcher wrote:
To determine the difference between consecutive elements of a loop, you can auto-index your array with a 0 initialized shift register, and wire teh element to the right side whilst calculating the difference.
The Absolute value function will allow you to find the magnitude of the difference.
How are you deciding between Ch1 and Ch2? When you say "sending Boolean true signal 3 times" do you mean 3 digital high value pulses? You can send boolean pulses with the digital waveform nodes:
Here I send 3 samples with Toggle - this alternates the signal. By default, the values are 0 and 1, so this means the output will be 0,1,0. The sample rate determines the rate of the waveform that is outputted whilst the number of signals determines the number of digital outputs you intend to use.
In your first snippet, I'd toss the first element of the resulting array because it doesn't mean anything. (The initial "zero" is a made-up number and doesn't represent real data. The data starts from 3, not 0.) What are your thoughts on this?
I'm not entirely sure, but the OP specified the values and pattern. It's true that taking the first value isn't the same as the others - they are differences while the first is just a replica, but that was the question
@cbutcher wrote:
I'm not entirely sure, but the OP specified the values and pattern. It's true that taking the first value isn't the same as the others - they are differences while the first is just a replica, but that was the question
Oh, I understand. I was just curious about your opinion of my opinion. 😉
billko wrote:Oh, I understand. I was just curious about your opinion of my opinion. 😉
Well, I suppose the truthful answer is I don't know what my opinion of your opinion is! But I sort of imagined that this question was counting with increment and decrement pulses, and so starting from zero sounded vaguely reasonable in my head. I'm not at all certain that's really what's going on, and I'm sure there are a wide range of situations in which I would indeed drop the first value (time taken to do something, like a reset as I saw in another thread a couple of days ago, for example - the first measurement was only the start whilst subsequent measurements were a stop and then a start).
You need to change what you're wiring into the shift register!
This snippet will give 5-0 = 5, 7-5=2, 2-7=-5. If you instead want 0-5=-5, 5-7=-2, 7-2=5, you should use the Negate primitive on the output of the subtraction.
