# Questions tagged [assumptions]

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### Assuming x real, simplifying or refining Im[1/(x+i)] doesn't yield anything

I think it is straightforward from the title, Simplify[Im[1/(x+I)], x > 0] spits out, Im[1/(x+I)] while I would have ...
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### Simplifying a sum

The expression I'm trying to do something with is Sum[1/(a!(s-a)!)b^(-(2a+1)/2) Sqrt[\[Pi]](2a)!/(4^a (a)!)Pochhammer[-a,k],{a,k,s}] where ...
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Why do the following commands $Assumptions = {Element[x, Reals], x > 0}; Solve[{x^2 == 1}, {x}] Solve[{x^2 == -1}, {x}] give ... 2answers 37 views ### Correctly restricting domain of parameters within Solve I have seen a few posts about this (such as this one), but none solved my problem. As a silly example, suppose I want to solve (1-x)^n = 0, knowing that n > 1. I ... 1answer 78 views ### Make assumption for function with variable argument I would like to assume that a>t[b_] for any b, such that e.g. Simplify[a>t[c]]==True. ... 1answer 53 views ### Many global assumptions I will do some calculations with probability distribution p[t] - which is a vector and each term corresponds to a probability of some event. Accordingly the sum over the terms in p[t] has to be one, ... 0answers 58 views ### Simplify with my own assumption to a^2+b^2=C^2 I am trying to use an assumption to simplify as a^2+b^2=C: ... 2answers 57 views ### Simplify the cubic root of cube assuming real and positive variable I know this is very simple but I couldn't find a reasonable solution for it in the archive. It seems that my Mathematica does not take into account the assumptions when it wants to simplify the ... 1answer 91 views ### Why are some of my assumptions ignored? In my opinion Mathematica should be able to further calculate and simplify the output of G1[...]. ... 1answer 39 views ### Integrate ignores Assumptions [closed] I'm asking Mathematica to compute: ... 1answer 77 views ### Calculating Limit with option Analytic->True and$Assumptions yields Series::cas

Overview I am using Limit with the option Analytic->True to check the finiteness of some expressions with generic functions ...
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### FullSimplify does not simplify at all

I have some problems simplifying things with FullSimplify. Suppose a matrix ...
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### Defining the domain of positive real numbers

I am trying to solve an equation by assuming that all the variables are real and strictly positive. I can use the keyword Reals for the argument ...
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### Using Series with Refine or Assuming to restrict the power

I have a system of differential equations which contain a singular point. To avoid the singular point, I am expanding the coefficients and solutions in a power series around that point. Due to the ...
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### Can the Assuming function be used with ContourPlot or DensityPlot?

I'm new to Mathematica, and for most purposes the program has served me well and been straightforward. However, I'm hitting a snag while trying to create a contour plot for the distribution function ...
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### How to use Assuming and If together?

I would like to compare variables t and u and print either Yes or ...
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### Linearity Assumption [duplicate]

I'd like to define a set of variables of this sort: {K1[t],K2[t],...} Adding a general assumption: all such variables are linear. I'd like to do this to avoid ...
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### Mathematica stuck at running symbolic multidimensional Fourier Transform

I'm trying to compute the analytical FT of a bidimensional exponential decay as follows: $f_E(\vec{x}) = \exp \left( - \sqrt{ (\vec{x} - \vec{\mu})^T \Sigma^{-1} (\vec{x} - \vec{\mu}) } \right)$ ...
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When one gives values to the $Assumptions variable, it seems to not matter whether you separate the conditions with && or just give is a list of the ... 1answer 34 views ### Reevaluating an expression when Assumptions have changed Is there a way to make this work? THM = TensorDimensions[M]; Assuming[ Element[M, Vectors[n]], THM ] Which gives: ... 0answers 41 views ### Not getting a solution to my maximization problem I want to solve the following problem: For$0.5<q<1$,$q<r<1$,$0\leq n$,$0\leq n_1<=\lfloor{n/2}\rfloor$, and$n_1,n\in\mathbb{N}$calculate$\arg max_{n_1} S(q,r,n,n_1) $as a ... 3answers 64 views ### Simplifying polynomial Roots with assumptions I have acquired the following root from a minimization problem: ... 0answers 61 views ### I assume that a parameter is real and positive, but Mathematica still assigns a phase to it If I run this line of code Assuming[{Element[a, Reals], a > 0}, TrigToExp[ComplexExpand[Sqrt[a]]]] I get ... 0answers 31 views ###$Assumptions not taken in account

Consider the following code : ...
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### Choose a branch cut using assumptions

I understand Sqrt function won't simplify expressions such as $\sqrt{x^2}$ unless there is an assumption that $x \in \mathbb{R}$. In my computation, I get an output containing an expression like this ...