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Apr
20
answered Integrating expressions with several terms and delta functions
Apr
19
comment First Order Conditions
The first thing I would recommend is to replace all Subscript with functions like a[k]. Subscript is really a pain to work with in symbolic computations. But even then, it would take significant effort to define the necessary rules to extract the desired derivative with index k+1. For finite sums, derivatives work if you first define the independent variables, as seen e.g. in this answer. But that doesn't directly generalize to your infinite sum, unfortunately. Try chris's answer.
Apr
19
awarded  output-formatting
Apr
18
comment power series or taylor series for transcendental equation
What is the expansion center? Looks like the function is non-analytic in $h=0$.
Apr
18
revised compute the gradient in high dimension
Simplified the finite difference function
Apr
18
comment Analogue for Maple's dchange - change of variables in differential expressions
I don't know much about Maple, but it seems from your examples that it's less "careful" when simplifying expressions: Mathematica leaves expressions unevaluated if it can't get a result that's valid generically or consistent with the given assumptions. So probably one would have to allow an additional Assumptions option in the dChange emulation to tell Mathematica which variables are positive, or complex, etc... so it has a better chance of inverting and simplifying the required relations. Anyway, I like the idea...
Apr
18
revised How to make traditional output for derivatives
greek symbol replaced
Apr
18
revised How to make Jacobian automatically in Mathematica
Added link to related answer
Apr
18
comment compute the gradient in high dimension
@novice Thanks for the correction, I edited the answer to also include the comment by MichaelE2.
Apr
18
revised compute the gradient in high dimension
Corrections for 3 or more dimensions
Apr
18
comment compute the gradient in high dimension
@MichaelE2 Oh sorry - I din't notice that. I'll double check and make the change. Thanks for pointing it out!
Apr
18
reviewed Close How to make work Plus function?
Apr
18
reviewed Close Nest-Recursion leads to overflow - Numerical calculation of Lyapunov exponents
Apr
18
reviewed Close NMaximize with constraints
Apr
18
reviewed Close Rebuild a polygon so it doesn't self intersect
Apr
18
awarded  numerics
Apr
17
comment Solving differential equation
It seems that someone downvoted this answer. Is there any reason why one of my two approaches would be bad?
Apr
17
revised compute the gradient in high dimension
Added order control
Apr
17
answered compute the gradient in high dimension
Apr
17
reviewed Close How to export Time Series Data?