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

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1answer
312 views

How to change machineprecision digits

I am trying to compute t0: ...
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3answers
208 views

Given a Boolean representation of a system, how can the Reliability Function be displayed as symbolic algebra?

Can Mathematica 9 convert a Boolean representation of an RBD to its symbolic algebraic form? If I have a simple series Reliability Block Diagram made up of 2 components, c1 and c2 bexpr1=And[c1,c2] ...
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1answer
304 views

Solve equation containing conditions (If expressions)

I want to solve the underneath equation. If I try Solve[AAA,dc], then I get no solution. Can anybody explain this? ...
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2answers
198 views

Derivative of the solutions by parameter

P0 = 0.1; K = 1000; Quiet[sol = Solve[{K*P*L == PL, P0 == P + PL, r*P0 == L + PL}, {P, L,PL}][[1]]]; complex = PL /. sol; Plot[complex, {r, 0.1, 2}] How can I ...
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1answer
211 views

x/.NSolve[f==g,x] does not work when f or g is the output of NDSolve!

I have been trying to put Points at the intersection of two curves, one of which is the ouput of a differential equation solved with NDSolve. The output being an Interpolation, NSolve cannot find the ...
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1answer
275 views

FindRoot on a 2D list of Equations

I have a $n \times k$ Matrix of data that I want to feed into an equation and solve for an unknown variable. I suppose I can always just convert the Matrix into a long Array but I'd like to learn how ...
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1answer
65 views

Weird behavior when solving a simple physics problem

I have the following code in Mathematica that represents two balls being thrown, one with a velocity v10 (6 in this case) and another ball thrown with a velocity v20 (its just dropped) one second ...
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3answers
72 views

High-Precision NSolve

I need to calculate the intersection of two curves f1[x_] := ((Zl ρ ) Exp[-x]) f2[x_] := (α k e^2 /x^2) Where ...
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1answer
101 views

Attempt to solve for Differential Equation - Acc, Vel, Pos in (x,y,z) [closed]

In the problem I'm working on, there is a tennis ball that is subjected to a headwind, tailwind, and crosswind. I am trying to use NDSolve in order solve for the position functions and to eventually ...
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1answer
121 views

How smart is Solve? Figuring out what tricks I should try

I'm trying to solve a large system (~10000) of linear equations using Solve, but the process keeps failing. As-is, I don't know whether it's failing because it's using too much memory or too much time ...
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2answers
91 views

Replace $z$ with interpolated function and plotting

I start off with this equation $z(x,y) = sin(xy)$. I create an interpolation from $0 < x < 5$ and $0 < y < 5$. I then use this interpolation on a simple function $w(x,y) = x + y + z(x,y)$ ...
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1answer
88 views

How can I speed up this multi-equation Solve problem?

I'm trying to solve a set of equations (chemical kinetics for a complex system, but don't worry about that). I ran it for 24 hours and I got no output. Here is the relatively simple code (I want to ...
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1answer
121 views

Finding the first five eigenvectors and values for a 500×500 matrix

I'm trying to find the first five eigenvalues and vectors of a matrix that has the following proporties: ...
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4answers
150 views

RSolve fails on a two-equation non-linear system

I have a system of just two recurrence equations, I need to solve them and so I use RSolve: ...
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1answer
160 views

marking the points of x-intercept on a plot

OK, I have a nice plot of some oscillating motion. I can read some stuff off the graph, but I thought it would be cool to show a dot where the curve hits the x-axis and a little label showing the ...
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2answers
110 views

Solving a system of 4 logarithmic equations? [closed]

I would like to solve this system of 4 logarithmic equations in Mathematica. a*log(b+d)=20 a*log(b*30^c+d)=125 a*log(b*180^c+d)=710 a*log(b*360^c+d)=1350 I am looking for the values of a, b, c, ...
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2answers
101 views

How to get a number from Solve [duplicate]

It's often useful to get just one number from Solve. I use the following construction for acquiring one solution from the expression returned by ...
0
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1answer
280 views

Finding equation of tangent line at a point [duplicate]

my function is defined as f[x_] = x^1.1 - 2.5 x^.5 I need to find the equation of the tangent line to the curve using the point slope form which would be something like f'[a][x+a]+f[a] a=1 and x=1 ...
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1answer
319 views

Solve the quadratic equation? [closed]

I can't seem to solve the general quadratic equation: Solve[ax^2 + bx + c == 0, x] Out[299]= {} It just outputs the empty list. How do I solve this equation?
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1answer
263 views

Solving a system of equations using subscripted variables

I want to solve this equation: X(i, j) + C*Y(i, j) = Z(i, j) Where ...
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1answer
2k views

How can I get the solution of complicated implicit function?

The question is what is the method to solve the implicit function has real and imaginary number. For example, The function is $$F(x,y)=(-I*x + 2*y^2)^2 + x^2 - 4*y^4*Sqrt[1 - I*x/(y^2)]$$ Although ...
0
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1answer
242 views

Reap and Sow From NDSolve solution

I want to get the answer of my NDSolve in the form of table (the value of each x and y). ...
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1answer
312 views

Solve telling me all my solutions are zero

I'm trying to use Mathematica to solve a complicated system of equations. Here is a screenshot of the equations, and what Mathematica outputs. The variables $v_i$ and $w_i$ act as constants in ...
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2answers
76 views

Solving a system of two equations

I have a system of two equations with the variables T and X that I tried to solve: ...
0
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1answer
78 views

Non Linear Equation Solving with Matrices

Suppose I have the following matrix equalities: A=X, B=Y where the left-hand side matrices are numeric and the right hand side contains non-linear combinations of unknowns. Since I have quite a few ...
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1answer
49 views
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1answer
88 views

How can I resolve the insufficient memory to complete the computation problem for solving function with iterated variables?

I am trying to solve for a value x in a function where the variables varies with iterations of K. Also, there is one variable called "rvsum" which is updated with a certain formula as well. I have ...
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1answer
164 views

Finding real roots for an eigth-degree polynomial

The context for this problem is identical to my first question. Unfortunately my previous result for $L$ was inexact since it was a relatively simple approximation. This time I have managed to produce ...
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2answers
111 views

Solving an Equation (Recursively)

I have the following Values: $a[0]=1;a[1]=0;a[2]=0;a[3]=0;a[4]=\frac{g_2}{20};a[5]=0$. I need to compute the value of $b[n]$ in the following equation $$a[n]=\sum _{m=0}^{n} (m-2) \;\;a[m] ...
0
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1answer
82 views

A problem with “RiccatiSolve::ncsol: Cannot compute a stabilizing solution to the matrix equation ”

I have a SSM ( State Space Model ) and I want to calculate its optimum gains unisng LQOutputRegulatorGains[] command. When I run the code, it solves the equations ...
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2answers
171 views

Solving a system of equations using matrix form

Please bear with me as I am a beginner at Mathematica. In the following system, all variables on the right hand side are known, except for w1, ...
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2answers
47 views

how to define roots of an equation as a function? [closed]

I need to solve an equation depending on 3variables in only one variables and define the roots as a function of the remaining variables? I used some thing like that: ...
0
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1answer
164 views

Nonlinear system of equations

I have been working to find an equilibrium solution for a Hamiltonian dynamical system. I have reduced the problem to the simultaneous solution of 3 equations: ...
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1answer
40 views

NSolve stalls when given an equation containing Log

Why does NSolve not work for this type of equation? ...
0
votes
1answer
107 views

Solving a system of equations where two variables can only be one of several discrete values

I want to solve a three-equation system, but I need to constrain two of the variables so that they can only take one of several discrete values that I would specify (this is a circuit design problem ...
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1answer
631 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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2answers
161 views

Eliminate variables by dividing two equations

how is it possible to divide two equations with Mathematica? I have the following code: ...
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1answer
72 views

Solving polynomial equations takes infinit time

I need to solve an polynimial equation, but when i try to use Solve or NSolve in mathematica, its cant find the solution in appropriate time (i interrupted calculation after 5 hour left). The ...
0
votes
1answer
188 views

How to enter and solve this equation in finite fields?

Is there a way in Mathematica 9 to enter and solve the following equation $p(x) = r^x$ where $p(x)$ is a polynomial whose coefficients are drawn from a finite field, and $r$ is a primitive root of ...
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1answer
69 views

LMS distance from a point to an InterpolatingFunction

I have a short script to NDSolve a second-order nonlinear BVP, which as its output produces an InterpolatingFunction object. I ...
0
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3answers
365 views

How can I solve my system of two simultaneous equations?

How to solve the system {b - a*Sqrt[a^2 + b^2 + 1] - a^2*(a*b - Sqrt[a^2 + b^2 + 1]) == 0, a - b*Sqrt[a^2 + b^2 + 1] - b^2*(a*b - Sqrt[a^2 + b^2 + 1]) == 0} ...
0
votes
2answers
191 views

Solving Within InverseCDF

I have the following input data: Remove["Global`*"] x = 5/30 // N; y = 0.8; μ = 0.2; T = 5; ρ = 0.8; σ (*to be determined*) And this is the given equation: ...
0
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2answers
229 views

Reduce on equations involving integrals

Here's part of problem from a college physics text: A time-dependent force F = (8.00 i - 4.00 t j) N (where t is in seconds) is applied to a 2.00-kg object initially at rest. (a) At what time ...
0
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1answer
812 views

Solving derivative of cumulative normal distribution log likelihood

I am a newbie and I'm trying to use Mathematica to obtain the symbolic Maximum Likelihood Estimation for a cumulative normal distribution. So far I have reached the step where I have the derivative of ...
0
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1answer
179 views

Solving a differential equation for a variable in a function

This may sound like a very trivial question, but I need to solve a differential equation as follows: ...
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2answers
140 views

How to get special solutions of this system of equations?

I only want to get all the solutions of this system of the solutions with a value of $k$, we have the same values ​​of $m$ ...
0
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1answer
315 views

I can't get Compile to work

I've got some problems with my code, and I try to make it faster. Some of you suggested me to split my problem, and I'm here... I post the same function with and without Compile. This is a support ...
0
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1answer
224 views

Solve not satisfying simple boundary conditions

I am trying to solve the following equations for the coefficients c1 and c2. ...
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1answer
143 views

Industrial Level Applications. Recipe for mixed notation of equations set

I am working with large (linear) equations set within Mathematica in numerical notation. For example, set from 4056 eq. is solved for a second, no more. There is no doubt, result is great. But even ...