Questions about the function Assuming[], the $Assumptions system variable, and the Assumptions option of functions such as Simplify[] and Integrate[].

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0
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2answers
94 views

Verifying inequality in Mathematica

I am trying to verify the following inequality Mathematica. This I wrote the fillowing code: ...
1
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1answer
46 views

Do double vertical bars in ConditionalExpression mean 'or'? [closed]

I have a very simple interpretation question. I think that double vertical bars in a ConditionalExpression given by Mathematica as the result of an integration must mean 'or', but I am hoping to ...
3
votes
1answer
61 views

How to assume all variables in my code are reals

I won't have any occasion to have any imaginary number in my code. If there are any, that is an error. So allowing the imaginary case simply hinders the equation manipulation and simplification. I ...
3
votes
0answers
79 views

Why isn't Mathematica listening to my assumptions?

I'm trying to simplify the expression ωplus := 1/2 c (I f V + Sqrt[4 k^2 - f (f + 8 I k) V^2]) so that I can get it in the form $a+i b$. I am using the global ...
0
votes
1answer
48 views

DSolve with coefficients and assumptions

The command below: DSolve[{s'[t] == l t, s[0] == 0}, {s[t]}, {t, 0, a}] gives the error DSolve::alliv: The function <...
1
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1answer
68 views

How to integrate with integer parameter in Mathematica?

I would like to integrate the following expression with N being Integer ...
8
votes
1answer
105 views

Adding irrelevant assumptions changes the result of Simplify

I've run into this problem a number of times. A typical example is Simplify[Sign[k], {0 < A, 0 < B, A*Exp[2*y] < k, y > 1}] which evaluates to $1$, ...
0
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1answer
69 views

Eigensystem with orthogonal elements in matrix

I have a matrix with 16 elements: matrix = {{f1, -f2, -f2, f3 }, {f4, -f1, -f1, f2}, {f4, -f1, -f1, f2}, {f5, -f4, -f4, f1}} I would like to calculate ...
8
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2answers
70 views

How do I SetDelayed $Assumptions

For some reason, $Assumptions := (Print["y"]; x > 0) evaluates the RHS immediately. I have code in which $Assumptions ...
0
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1answer
44 views

Assumptions with Multiple Rules

What is the correct way to add more than one assumption while integrating? I am attempting to evaluate the following integral and Mathematica is just stalling, so I'm wondering if my assumptions are ...
0
votes
1answer
55 views

Simplify assuming $x$ is small [closed]

I would like to assume that $x$ is small so that values of the order $x^2$ (and higher orders) are negligible. For example, I would like Mathematica to return $1-2m$ when I ask it to simplify $(1-x)^...
0
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0answers
31 views

Using assumptions with Integrate [duplicate]

I open Mathematica and execute this code: ...
0
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0answers
45 views

Impose conditions on differential equations

This is my first post in Mathematica Stack Exchange, so thanks for your help and sorry for any rookie mistakes. I am solving the Einstein equations for two vectorial pertubations h_Alpha and v_Alpha ...
1
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1answer
37 views

How to specify assumptions without typing out functions

So I want to add assumptions in carrying out integration. I know I could use the Integrate function: Integrate[V Exp[-x/a] ,{x,0,10}, Assumptions->a>0] but ...
1
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0answers
61 views

Assumptions aren't working in this sum

I have a sum that should be real: FullSimplify@Sum[1/(α n^4 + β), {n, 1, ∞}, Assumptions -> α > 0 && β > 0] But the result have involved even ...
1
vote
0answers
61 views

Limit not evaluated [closed]

I hope this question ha not been asked since the limit is evaluated in 1 not at 0 or infinity. I do not know how to ask Mathematica to find the limit as n -> 1 of the following function: ...
0
votes
0answers
30 views

Finding parameters that give constrained eigenvalues of matrix

I want to obtain the eigenvalues $x_1,x_2,x_3$ of a hermitian, off-diagonal matrix, {{0, Conjugate[d], Conjugate[g]}, {d, 0, Conjugate[h]}, {g, h, 0}}, under the ...
1
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2answers
73 views

Minimization of a function with non-numeric parameters?

I have the following problem (in Mathematica) I want to calculate the following expressions: ...
7
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0answers
83 views

Need explanation on strange behavior of Simplify under given assumption

This is quite surprising to me. Simplify[a == b, {a == {1}, b == {1}}] a == b does not evaluate the equality, while <...
2
votes
1answer
88 views

Getting wrong result when Integrating under an assumption [duplicate]

The simple integral $$\int_0^b \cos\left(\frac{2\pi m(y-\eta)}{b}\right) \cos\left(\frac{2\pi \eta}{b}\right)\mathrm{d}\eta$$ can be easily evaluated by Mathematica as, ...
0
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1answer
112 views

Understanding the symbolic solutions of a system of differential equations

I'm trying to solve a simple system of differential equations but get outputs i just cant grasp, they seem way overkill. Someone said it might be because mathematica interprits the constants as non-...
1
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0answers
32 views

Hidden assumption in Mathematica integration [duplicate]

If I do Integrate[Exp[I*omega*t],t], it gives me $\frac{1}{\omega} e^{i \omega t}$, as expected in most of the cases, except when $\omega$ is 0. Mathematica seems ...
0
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0answers
50 views

vector with conditions/assumptions

Probably I just don't get it and it is because it's friday morning. I want to create a systems description fSys = {{x2}, {u g[x] + h[x]}}; However, there is a ...
2
votes
1answer
54 views

Resolve assuming $x$ is real when $x$ is a free variable in a ForAll expression

I am using Mathematica to check whether a function is positive semidefinite. I have come upon an odd situation. Namely, when I input ...
1
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1answer
73 views

The assumption in integration does not work?

I am new to mathematica. Here is the question. I try to do the following integration with the assumption that k1<0, k2<0 and k1,k2 are real number. However, the result includes \sqrt{k1}? ...
0
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1answer
60 views

Same integral gives different results with assumption

b = 1 k = 12560 r = 500 res = Integrate[Exp[I*k*x*Sin[o]]/(r + x*Sin[o]), {x, -b/2, b/2}] resab = Abs[res]^2 Plot[resab, {o, -Pi/20, Pi/20}, PlotRange -> Full] ...
2
votes
1answer
80 views

Constrained Sum evaluation [duplicate]

I need to sum up F[x1,x2,...] over x1,x2,... where I have a constraint: x1+x2+...=n (n=positive integer number). For example, I have F[x1,x2] and x1+x2=3, so for the sum I get F[3,0] + F[2,1] + F[1,2] ...
3
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1answer
46 views

Restrict list to reals for statistics

I get conjugates in output when running this: Clear[X]; X:={x1,x2,x3}; Assuming[{Element[X, Reals]},StandardDeviation[X]] What is wrong with the code?
3
votes
1answer
58 views

Why doesn't a real variable's conjugate evaluate to itself?

I have this code (it's just a snippet to exemplify my issue): Assuming[Element[a, Reals],Conjugate[a]] Which results in the output: ...
4
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1answer
44 views

Simplify With Assumptions Not Using Distributive Property Of Dot Product

Given the following expression Assuming[(n | d | t) ∈ Vectors[3, Reals] && n.t == 0, FullSimplify[(n + d).t]] Why does mathematica give me the below ...
0
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1answer
100 views

How to impose Assumptions for a list of variables?

I've got an $Assumptions variable that I'd like to apply to my whole notebook, looking like so at the moment: ...
2
votes
1answer
91 views

How to make Simplify (and FullSimplify) give a default output if $Assumptions are contradictory

I have a function (deep inside my package) that looks like ...
2
votes
3answers
124 views

Adding more specific assumptions to Integrate

Let's say I would like to find a symbolic form for the integral $$\int_0^{2\pi}\sin^nx\,\mathrm{d}x$$with the added condition that $n$ is not only an integer, but an even one at that. Can this be done?...
9
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2answers
150 views

Problem with Identifying Complex Components

I am trying to isolate out the real and complex terms in a fairly large expression. During the process, I have made several assumptions that last throughout the entire process. ...
0
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1answer
57 views

Assumption that a parameter is real [duplicate]

I'm making some calculations, where I use the command Conjugate[f[x]]. In the function f[x] appears a parameter J, which is Real. How can say mathematica that it should not take the Conjugate of J? ...
1
vote
1answer
186 views

Dealing with indicator functions

I am calculating the integral of two indicator functions with Mathematica. I'm having difficulty in imposing assumptions. What I have done so far: To define an indicator function: ...
3
votes
1answer
170 views

How to make Maximize function successfully maximize in general?

Having looked at Maximize Documentation SO: Mathematica: Commands return no output, but itself. Bug? Problem with Maximize Why won't Mathematica Solve a set of two equations for one variable? ...
4
votes
0answers
119 views

Puzzled by Assumptions [duplicate]

I don't know if this has already been discussed. Integrate[BesselJ[2 m + 1, x], {x, 0, ∞}, Assumptions -> m ϵ Integers] ...
8
votes
1answer
118 views

evaluation of the sum of KroneckerDelta

I need help. I need to know why the next code doesn't simplify in Mathematica 10 but it does in Mathematica 8. I need some similar in version 10. What can I do? ...
5
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0answers
53 views

External and internal Assumptions on `PiecewiseExpand` and `Mod`

After this question I'm intrigued about the different behaviors depending where and how the assumptions are given. ...
2
votes
2answers
87 views

Integration result with incomplete beta function

I'm doing some calculations (double integration) which results in the incomplete beta function occurring as an end result. My input is: ...
1
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0answers
103 views

Assumptions don't work as expected in FourierTransform

The 2D rectangular function and its Fourier Transform is $$ g_{in}(x,\,y) = rect(\frac{x}{x0}) \, rect(\frac{y}{y0}) \quad \xrightarrow{\mathscr{F}} \quad G_{in}(u,v) = x0 \, y0 \, sinc(\pi u x0) \, ...
7
votes
1answer
136 views

Is it possible to add some pattern to $Assumptions

I apologize if it is a too elementary question but I could not find the appropriate documentation so far. My goal is simple. I would like to add some assumptions that are defined in terms of ...
0
votes
1answer
86 views

How to simplify an expression with assumptions

I have a matrix of the form: Tvol // TraditionalForm $$\left( \begin{array}{ccc} 1 & \frac{\delta I_1(\kappa )}{I_0(\kappa )} & 0 \\ \frac{I_1(\...
4
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0answers
108 views

Multiple Constrained Sum

I need to perform a multiple summation, that obeys some conditions. This arises in the study of a statistical physics model. q=Exp[-β]. I would like to ask if ...
1
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1answer
102 views

How to assert that a list of variables is real in a nice and clean way

You can use the function Element to say e.g. $x,y,z\in\mathbb{R}$ via Element[x | y | z, Reals]. Now if I have a list of ...
2
votes
1answer
76 views

Mathematica does not distribute conjugation when used with Assuming sometimes?

If I input: Assuming[$x_{-} \in$ Reals, FullSimplify[Conjugate[$e^{i x_1}x_2$]]] Then the output is: $e^{-ix_1}x_2$ As it should be. And if instead I do: Assuming[$x_{-} \in$ Reals, FullSimplify[...
0
votes
1answer
72 views

How to disqualify a rule [closed]

Executing this line Assuming[x < 0, x -> 10] Expected output: False Say x -> 10 is a root of a polynomial ...
1
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3answers
155 views

Identify a scalar, a list

I have a symbolic scalar m2 and a symbolic list (representing a 3x3 matrix) A. I want a function which does something like: <...
0
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0answers
39 views

Need help with solving inequality under assumptions [duplicate]

I seriously need help for my research. I need to solve an inequality with several assumptions. I tried many times with Reduce but it did not work out properly. Sometimes the results I get are simply ...