Questions on the analytic and numeric equation solving functions of Mathematica (Solve, Reduce, NSolve, FindRoot, DSolve, RSolve, etc.).

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1answer
71 views

Notebook keeps running when Solve for variable

This might be a simple question for the most of you, but I am very new to mathematica so please bear with me. I'll refer to the code below: ...
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1answer
99 views

Two questions on strategies for quantifier elimination

With the help of people here I was able to solve several cases similar to IC3 but this case - unlike the other cases - does not return an answer. I will try to run it for a day with 8 processors but ...
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1answer
39 views

Help with Reduce, quadratic system of inequalities

I'm trying to obtain an equivalent system of inequalities to the one below but without the variables x and z. Somehow Reduce just repeats the command. ...
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1answer
80 views

Coefficient of function different than polynomial

My question arise from the problem that Mathematica can't solve the equation $$ \text{Solve}\left[e^{a-x} (0.0299584 a+0.1 b-0.0299584 x-0.152913)-0.9 a+0.9 b+0.9 x+0.18=0.0498614 e^{-x} \left(e^a ...
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1answer
36 views

Storing solution to x and y [duplicate]

If I do sol=Solve[{2x+2==y,3x+9==y},{x,y}] then Mathematica will tell me {{x -> -7, y -> -12}} But I would like to ...
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1answer
83 views

A question about using Reduce [closed]

Can someone help decipher what is the meaning of this computation that Mathematica has done? ...
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1answer
127 views

Trying to solve a transcendental equation involving bessel functions

I've never used Mathematica before and am trying to numerically solve equation (12) from this paper: http://arxiv.org/abs/hep-ph/9907218v2. Ideally I'd be able to find the smallest value of $x_{n\nu}$ ...
0
votes
1answer
51 views

inverting this equation [closed]

I'm trying to inverse this equation Z = X + X^2 / 2 but couldn't wrap up my head around it. If anyone can provide a step by step solution to this it will be ...
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1answer
446 views

How to find the inverse a symbolic matrix that Mathematica thinks might be singular

I have a square matrix depending on a parameter "a". When "a" has a numeric value (eg 2.1 * 10 ^ 8) through the inverse function Inverse[] I can invert the matrix. If I write the matrix as a function ...
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1answer
51 views

Solve equation with two different sets of replacement rules

I want to solve eqn for c0. I want to do it with both replacement rules. I realize I could just use solve twice, once for subsCoke, and once for subsPepsi. I'm trying to do it in just one Sovle to ...
0
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1answer
120 views

2 Equations continuous at a point

I want to get continuous point between two equations. My equations are: ...
0
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2answers
164 views

How to get a solution for the following equation?

When I try to solve this equation using Mathematica: Solve[Exp[b*x]-c*(x^2)-a*x-1 == 0, x] /. {a -> 6.336, b -> 8, c -> 32} I don't get any result and ...
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1answer
42 views

Error when solving equations constructed with Table [duplicate]

I have a couple of questions about the problem I am trying to solve ...
0
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1answer
53 views

How to ignore terms containing in the summation of multiplications

n=4;L=3; p0[n_Integer]:= Product[ Sum[Subscript[r, k][l, l], {l, L - 1}], {k, n}] // Expand; How to ignore terms containing three or more multiplications of [2, ...
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1answer
157 views

Why is my PageRank result in Mathematica converging this way?

I am using this technique to find the PR of these 3 pages. It converges to something it shouldn't be. I tried the same iteration in Java and 2 pages come up with 1.333 and the other one as 0.666. ...
0
votes
1answer
68 views

Checking result for expression

I want to verify the following result: $\sum _{y=2}^{n+1} \left(\sum _{x=y-1}^n \frac{1}{x-y}\right)=n \left(H_n^{(1)}-1\right)$ In Mathematica i try with: ...
0
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1answer
74 views

Why Solve won't work for user-defined function, used for system solving? [closed]

I have a list of x-es, that I transform into a list of tx-es. Also tao is my user-defined function that I don't know the parameters of, but I do know the values I get when I put the tx-es in it. And ...
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1answer
161 views

Reduce Cannot Solve Complicated Function

As per the answer to this question: SolveAlways rejects inequality, I tried the following commands: ...
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1answer
83 views

SolveAlways rejects inequality

I have two functions of x, f and g. f[x] = g[x] + 2, ...
0
votes
3answers
97 views

Reduce of a table [duplicate]

I have a table for example: t = Table[k,{k,5}] which returns {1,2,3,4,5} and for every element in this table I want to check ...
0
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1answer
185 views

NDSolve + FindRoot for Bessel Zeros

I am trying to use a solution given by Michael E2 in this topic: ...
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1answer
188 views

Solve Probability of Distribution

Why does this work: Solve[Probability[x <= t, x \[Distributed] NormalDistribution[]] == 0.95 ,t] But this doesn't: ...
0
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1answer
158 views

Plotting a function only non-zero for discrete values of argument

I have a function like: $$ f(E)= \Sigma_{n=0} \Sigma_{\ell=0} \, \delta\left(E+\frac{\ell+2n+2} {R\sec{\rho}}\right) w(n,\rho,\ell)\,, $$ i.e. the function is zero unless $$ ...
0
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1answer
62 views

Issues FindRootPlot command

I've had some fun playing around with FindRootPlot for a simple system of equations: ...
0
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1answer
320 views

DSolve to solve a system of differential equations [duplicate]

I need to solve a system of differential equations as follows: ...
0
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1answer
136 views

How to return the rhs of a transformation rule from within Compile[]

I have defined the following function: ...
0
votes
1answer
199 views

Solve[polynomial, x, Reals] doesn't get all real roots or correct ones?

My main confusion is about the difference between the two code blocks at the end of this long spiel, but the spiel contains the code to create the polynomial if its coefficients are helpful for ...
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2answers
456 views

Classification of a linear system of equations with a parameter

I need to get every possible value of k that returns infinite number of solutions or no solution to this system: ...
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1answer
529 views

Equation with complex numbers and 2 variables

I have an equation: eq = 1 + ( 9 / ( s*(s + 9) ) )*( k/(s + b) ) == 0; where s == -2 + 2I (...
0
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1answer
427 views

How can I solve a set of non-linear equations?

I was wondering whether someone can give me an idea on how I can solve a set of non-linear equations with an unknown exponent This is what I have: Known values: N, R Unknown values: λ, α, J ...
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1answer
452 views

How to find the zero of a function?

I want to find out when a function has a real root. I first made a RegionPlot3D when the function is zero. ...
0
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1answer
222 views

Find root of a function defined as a Module

I have a simple module like BCdet[x_, y_] := Module[ {AuxMat}, AuxMat = Mat /. {f -> x, A -> y}; Det[AuxMat] ] where ...
0
votes
1answer
118 views

How to simulate a multivariate recursive system from a list

New to mathematica, trying to use Eric Swanson's Pertubation AIM program to solve DSGE models. His code produces a solution as a list or a table. My question is how do I use this list to simulate the ...
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1answer
254 views

How to nest the output of FindRoot in a table of Derivative evaluations?

I am using ParametericNDSolveValue to numerically solve an ODE system, which I then use to find the definite integral of one of the variables in the solution for different values of a parameter. Here ...
0
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1answer
88 views

Solving one equation, then inputting the values into another for NonlinearModelFit

Considering the equation a*x^3 + a*x^2 + x + b == 0 I'm looking to find the best value for a and ...
0
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1answer
184 views

solution of differential equation

I have the following code that gives you a phase portrait of a 2d system and I can't understand what means the 3rd and 4th line (sol1 and sol2). ...
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1answer
95 views

Plotting query - same values on Y-axis / viewing data

I'm new to Mathematica, and have numerically solved two similar functions with the following code; ...
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1answer
370 views

Upper bound for x

I want to ask a question about Reduce. I have a function, say f[x]. When I use the command ...
0
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1answer
146 views

Difference between FindInstance and NSolve

Assume that ...
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1answer
92 views

Collecting roots of different equations and create a list

I solve two equations and have two solutions one by each equation. I want to create list of these roots. Could anyone please help me? Appreciate it. m02R150 = FindRoot[P1 == 0, {E1, 0.07, 0.1}] ...
0
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1answer
177 views

ContourPlot of a complicated function

I have the function $pot_1(x,y,z)$ which is given in analytical form. So, in order to plot the contours at the primary planes $(x,y)$, $(x,z)$ and $(y,z)$, I use the following ...
0
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1answer
192 views

Evaluating derivatives for use in solve

I need to evaluate the derivative of a function. My function looks like approx[vector_, x_] := Sum[vector[[n]]*Basis[n - 1, x], {n, 1, Length[vector]}] and I'm ...
0
votes
1answer
515 views

Why does Mathematica fail to solve my equation?

I am trying to solve an equation using Mathematica, but I keep getting the following error Solve::nsmet: This system cannot be solved with the methods available to Solve. More importantly, ...
0
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1answer
165 views

Manipulate[]'ing complex roots of an equation using a 2D slider [closed]

I want to make a demonstration of how the complex roots of a polynomial change when I alter the coefficients. Here is my attempt: ...
0
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1answer
228 views

How to express endogenous variables in terms of exogenous variables?

I have 11 endogenous variables (RD, NR, WR, Q, NQ, R, L, W, NU, C1, C2) and two exogenous variables (EE, K). I'm trying to find $RD = f(EE, K),\, NR = f(EE, K),\, ...,\, C2 = f(EE, K)$. Hence, I ...
0
votes
2answers
157 views

How to use Solve rules as a function body?

Solve gives me an expression which I want to use as the body of a function. Rather than run Solve every time inside my function ...
0
votes
1answer
166 views

Assign the result of Solve in a list [duplicate]

Possible Duplicate: Assign the results from a Solve to variable(s) I want to assign the results of a Solve command in a list. For example Solve[-((287 s^3)/50) == 0, s] returns {{s -> 0}, ...
0
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1answer
352 views

(N)Solve does not solve equation

I am trying to calculate where a beam hits a mirror. The mirror is described by this curve (two facing spherical mirrors): ...
0
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1answer
278 views

Iterative way to find roots of confluent hypergeometric function

I am trying to find roots of confluent hypergeometric function and I wonder if I can choose the initial guess by the choice of $\beta$. ...
0
votes
0answers
31 views

Plot solution of NSolve depending on the parameter

I would be very grateful if someone could help me with this: I have an equation (which is quite difficult one involving PDFs, CDFs of some distributions etc.). The only way it can be solved is ...