Tagged Questions

How to manipulate expressions structurally, not necessarily complying with the rules of algebra.

64 views

Derivative of vector dot product with respect to a vector

I have the expression: Transpose[gvecI, {2, 1}].x (m[1] + m[2]) gvecI and x are [3x1] ...
49 views

Position not working? [closed]

I have the list: myList={0,0,0,a,b,c,0,0,d} I need to find the positions of all elements that are non-zero. I do like this: ...
81 views

Find sub-sets of vanishing additions or subtractions from a list?

Let's say I have a list L containing n numerical numbers. Now I want to find all sub-sets of ...
58 views

Dropping rational coefficients

I have a list of expressions (they all are exact numeric quantities, not containing any variables), some of them have integer or rationals coefficients, or complex coefficients with rational or ...
75 views

Trouble simplifying using Replace

I have the following expression: w.a.b.r+w.c.d.r I want to get: w.(a.b+c.d).r So far I used ReplaceRepeated: ...
52 views

How to remove parts of an expression

I have an expression where terms Transpose[R].R appear. R is a matrix with the property Transpose[R].R=IdentityMatrix[3]. How ...
300 views

How to get a list of monomials of a polynomial without coefficients?

Giving a polynomial, say a x^2 + b x y + c y^2 MonomialList[a x^2 + b x y + c y^2, {x, y}] just gives ...
2k views

How can I transfer mathematical expressions between Mathematica and Maple?

Is there a simple way to copy mathematical expressions between Mathematica and Maple (or at least in one direction)? I mean only expressions built from numbers and predefined mathematical functions, ...
51 views

Boundedness of an expression

First post on this part of the stackexchange network, I was just wondering if Mathematica allows one to quickly see if an expression is always within a certain range given values for the parameters it ...
206 views

Is there a way to use array of data as a function variable?

I have a data that looks something like. {{1,1},{12,1},{7,9},{10,14}, ...... } I want to see if there is an easy way to apply this array of data into a ...
73 views

Factor a specific sub-polynomial?

Consider the following example for a polynomial in several variables: ...
62 views

Sequence of arbitrarily many variables separated by commas? [closed]

I am wondering if it is possible to produce an input such as x[1],x[2],x[3],...,x[n] for an arbitrary but fixed amount of n ...
141 views

How I can count multiplications in an experssion?

Next task to complete: Count *-symbol in such expression as a + s^2*b - c/y + o^3 + n*m*u (in this case count of ...
50 views

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What options need to be set for Simplify to perform a certain manipulations similar to FullSimplify?

Simplify performs algebraic transformations and is fast, while FullSimplify tries a wide range of transformations involving ...
47 views

How can I manipulate a long expression to order it by factors/derivatives of a particular function?

I have a Mathematica notebook that generates a linear expression involving derivatives of a given variable. Expanded (and simplified for our purposes), it looks something like this: ...
50 views

2D plot using Manipulate command [closed]

Can anyone tell me what the problem is with the following code: y[x_ a_] := Sin[x (1 + a x)] Manipulate[Plot[y[x a], {x, 0, 6}], {a, 0, 2}] However, the ...
294 views

Embedding StreamPlot in Graphics3D

I am trying to visualise the action of the infinitesimal generator of a Lie group on the solution of a 2-ODE system drawn in the 3D space (t,y1,y2): t is time and y1,y2 are the two dependent ...
167 views

Is there a way to control which special forms Normal converts?

Normal documentation reads: Normal[expr] converts expr to a normal expression, from a variety of special forms. But is there a way to control which special ...
50 views

Analogue of Maple's identify command in Mathematica [duplicate]

In Maple there is a useful command identify that tries to find a closed form expression based on its numeric approximation. As far as I know there is no built-in ...
81 views

Extracting subtree for a TreeForm

How can I extract an entire subtree from a TreeForm starting from a specific point of the tree? Because with Extract or Part you can take only that specific point...
56 views

How to force evaluation of an expression with Part left unnevaluated?

My goal is to minimize a real valued multi-variable function averageFreeEnergyDensity. The function accepts an integer argument ...
271 views

Print all numbers from a sequence which don't contain the digit 7

so i have this: Cases[RecurrenceTable[{a[n + 1] == 7 a[n] + n, a[1] == 1}, a, {n, 7}], Except[7]] But i noticed that it will only exclude numbers that are 7, and ...
93 views

Loop in a loop, or how to evaluate complex expressions

I need to find $h_{0j}$ for every $1\leq j\leq300$, where \begin{multline*} h_{0j} = \sum_{q=1}^{Q}g_qe^{-\lambda_q j\Delta}\frac{e^{\lambda_q\Delta}-1}{\lambda_q} + \sum_{p=1}^{P}\frac{e^{-\alpha_p ...
1k views

Scan vs. Map vs. Apply

I cannot understand the difference between Apply, Scan, and Map. I have tried to play with ...
317 views

Why is ReplaceAll behaving like this?

I'm learning to use the ReplaceAll function and I found the behavior of which is quite confusing. For Sqrt[f[x, y]] /. f[___] -> u Mathematica returns ...