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1
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1answer
90 views

Force Mathematica to return numerical answer to (relatively) complicated differential function

I am trying to take the Laplacian of the LogDet of a 2x2 matrix that I call V\[ConjugateTranspose].V, and actually get a number out at the end. Why does Mathematica ...
1
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2answers
44 views

Differentiation of an unknown function

I have to take the partial differentiation of an unknown function. For example, take the unknown function to be $g(x)$. Then it's derivative w.r.t $x$ is $g'(x)$. By default, Mathematica ...
0
votes
1answer
51 views

Replacement of terms/Pattern matching involving products of derivatives of a function

In delving into Ramanujan summation, I'm trying to get a hold of the relations of the form $$\sum_{n=0}^\infty f(n)=\dfrac{h\frac{d}{dx}}{{\mathrm{e}^{h\frac{d}{dx}}}-1}\int_{0}^\infty ...
1
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2answers
73 views

How to take derivative with respect to logarithmic function [closed]

I have a function g as a function of x; i want to take derivative of g with respect to ln x, i.e. dg/d ln x where g= ax^2/(1+ax^2/r^2)
1
vote
1answer
88 views

Derivative of a plot [closed]

I plotted a graph numerically, so I don't have a definition of the plotted function. Now I want to plot the derivative of this graph. Is there any way to do it in Mathematica? I have the following ...
6
votes
1answer
192 views

Better replacement rules to perform this change of variables?

In cosmology, it is common to work with both a normal time variable t and a “conformal” time variable τ, which is defined such ...
0
votes
1answer
43 views

Differentiating an equation [closed]

Hi all I need to differentiate an equation: K = a*b*(c-h)^2*(2*c+h)*PI()/(3*c*c) I need to find dK/dh. How do I evauate this in mathematica? is this correct? ...
1
vote
1answer
65 views

How to compute the composition of linear differential operator [duplicate]

For example, I have to write down the differential operator below as a polynomial in $\partial$ $$(\partial-f_n(x))(\partial-f_{n-1}(x))\cdots(\partial-f_1(x))$$where the product the the composition. ...
0
votes
0answers
56 views

Determination of Ricci tensor and Scalar curvature from veirbeins

Consider the following metric: $ds^2=h(r)\bigg(dr^2+r^2\big(d\theta^2+\sin^2\theta ~d\phi^2+(d\psi+\cos\theta ~d\phi)^2\big)\bigg)$ We can try to compute the Ricci scalar of this metric by using ...
0
votes
1answer
65 views

Differentiating two tables x and y?

I have two tables x and y with x={673,674,675,...} and y={0,1,2,...} and delta=dx/dy. I would like to know how delta can be calculated knowing that delta is the derivative of x divided by the ...
6
votes
1answer
113 views

Taking the derivative of a function with indexed variables

I have a number of functions that depend on a variable x. I am using a second, integer variable to index these functions, i.e. something like ...
1
vote
1answer
47 views

Specifying independence of a variable in a function

I am dealing with a function of a finite number of variables and among the operations I wish to do is to differentiate it repeatedly with respect with any of the variables. Now this function happens ...
0
votes
1answer
50 views

What's the difference between this differentiation? [closed]

I've tried to evaluate a sum and get a result in terms of Zeta function. And I have results in two forms: ...
2
votes
1answer
230 views

Solve ODE $d^2u/dx^2 + u/A = 0$

How can I solve following ODE with Mathematical: $$d^2u/dx^2 + u/A = 0 \quad (\text{or } \ C),$$ with the conditions: $$ \left.\frac{d^2u}{dx^2}\right|_{x=0} = 0, $$ $$u(x=0) = B$$ and ...
1
vote
1answer
62 views

Differentiation of Vector Equation

Is it possible to get symbolic derivatives of equations with vectors as arguments without specifying every vector element explicitly. Something like ...
4
votes
1answer
190 views

Mathematica package for supergravity and superstring theory

I am looking for a Mathematica package that can manipulate tensors for supergravity, string theory or M-theory. I am particularly looking for a package that can do spinor and Clifford algebra ...
1
vote
2answers
61 views

Simple derivative not working [closed]

I'm a complete newbie to Mathematica. I've been using Wolfram Alpha Pro as well as MS Mathematics for a few months but wanted to dive into using a more powerful tool. I'm having a problem with ...
0
votes
1answer
74 views

Unable to configure a system of differential equations

My differential equations have been written as ...
1
vote
0answers
129 views

Extract coefficients of differential form in package RGTC

I am using the Package RGTC to do some calculations in Supergravity. It allows to define differential forms after specifying a co-frame. I am working in with the 10d coordinates ...
0
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1answer
65 views

Using Derivative with list in curly brackets

I'd like to make a formula for a sum containing Derivative where the number of arguments in the latter depends on an input parameter n. Also involved is a list ...
9
votes
1answer
321 views

Inconsistent results of second derivative of inverse fourier transform

I am trying to get the Green's function of a toy diffusion equation $$\frac{\partial^2 u(x,t)}{\partial x^2} = \frac{1}{\alpha^2}\frac{\partial u(x,t)}{\partial t}$$ with Mathematica 9. Then solve ...
5
votes
1answer
114 views

Apparently contradictory output from Series and D

I defined a function as: g[b_] := Integrate[f[n]Exp[-b DA (n.u)^2], n] Obviously D[g[b], b] /. b -> 0 gives ...
3
votes
2answers
170 views

Differentiating a Cumulative Distribution Function which has a discontinuity at $0$

I want to take the derivative of a distribution function which has a discontinuity at $0$. Here is the function: ...
1
vote
1answer
293 views

Solve a total derivative - independent vs. dependent variables

I am trying to force mathematica to solve a generally defined function for d lp: In a reduced version, w depends on l2, ...
1
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3answers
2k views

Find dy/dx given an equation

Here's a homework problem from the Coursera course Calculus: Single Variable by Robert Ghrist Find the derivative $\frac{dy}{dx}$ from the equation $x \tan y - y^2 \ln x=4$ I wanted to check my ...