Gradient is zero yet exists
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Hello gradient (140,150), the answer is 0, but it exIhere is my error please? Also, is diff for calculating the derivative? GS.
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Stephen23
2017-9-6
Why would you expect
>> gradient(140,150)
ans = 0
to be non-zero? You are asking for the gradient at one point... to be honest I am surprised that it does not return NaN. Did you read the gradient documentation to know what the two arguments are for?
Perhaps you really wanted to do this:
>> gradient([140,150])
ans =
10 10
"Also, is diff for calculating the derivative?"
Did you read the diff documentation? It answers your question, right on the very first line.
6 个评论
Gavin Seddon
2017-9-7
Stephen23
2017-9-7
"Is it best to use dIff?"
Different tools do different things. Is a hammer better than a spade?
Gavin Seddon
2017-9-13
John D'Errico
2017-9-13
编辑：John D'Errico
2017-9-13
Hmm. "Is a hammer better than a spade?" After a great deal of careful thought, I can only ascertain that some fellows named Art G. and Paul S. have told us that I'd rather be a hammer than a nail. Perhaps more research is necessary on my part. Time to revisit some more music that many of those reading this comment will not even recognize. ;-)
Stephen23
2017-9-13
@John D'Errico: while we should clearly acquiesce to Messrs Simon and Garfunkel's authority on the subject of hammers vs. nails, how do spades fit into this? It leaves us with some small conundrums to resolve: is the relationship between spades, hammers, and nails associative and/or commutative? Can this be generalized to all tools? Who can write the simplest vectorized code for this?
John D'Errico
2017-9-13
编辑：John D'Errico
2017-9-13
I think I need next to visit Scarborough Fair. They have a large library there, wherein I can do the necessary research. For example, are spades lesser or greater than nails? I think what matters is if some sort of transitivity relation exists in this matter.
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