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

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1answer
185 views

Differential equation solution

DSolve[y''[x] + (a - (b*x^2 - c)*x^2)*y[x] == 0, y[x], x] I couldn't solve this equation, please help
0
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0answers
41 views

Don't understand results from solving polynomial equation [duplicate]

I attempting to solve an equation for x so that I may then switch x & y to get the inverse function. This is the code I have for solving for x: ...
2
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1answer
118 views

Approximating Magnitude of Solutions

I was recently lecturing on the hierarchy of functions in a calculus class. Discussing the fact that eventually any exponential growth function will overcome any polynomial. As an example, I tried ...
0
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1answer
78 views

FindRoot not working for a system of two equations [closed]

I am using to find a solution for two dimensional system. Here is the code I use ...
1
vote
1answer
157 views

Solve for when two symbolic complex numbers are equal

I'd like Mathematica to to show that two complex numbers $a + b i$ and $c + d i$ (with real coefficients $a, b, c, d$) are equal if and only if $a = c$ and $b = d$. The obvious thing does not quite ...
1
vote
1answer
80 views

Numerically solving a transcendental equation as a series

Given a transcendental equation $f(x,y)=0$, is there a way for Mathematica to automatically solve the equation as a series? I already know that I can use ...
4
votes
4answers
159 views

Implicit function theorem to higher order

Consider f[x_, y_] := Csc[0.482` y] Sin[0.963` x - 0.482` y] + 3.247` Csc[0.333` y] Sin[0.667` x - 0.333` y] + 5.049` Csc[0.119 y] Sin[0.238 x - 0.119 y] ...
0
votes
2answers
136 views

Don't understand results from solving easy polynomial equations

I am alarmed by the behavior of Mathematica (9.0) when given the following simple set of equations to solve: ...
6
votes
2answers
368 views

Time evolution/dynamics of circular plate with hole (Biharmonic equation and stiffness)

On this Mathematica.SE form, there exists information on how to use Mathematica to demonstrate the vibration of a circular membrane and the deflection of an orifice plate (the latter I had raised ...
1
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2answers
154 views

Solving an equation containing a Factorial

I have a question regarding the code to solve a particular equation. This is the equation: 364! / [(365-n)! * 365^(n-1)] <= 0.5 and I need to solve for ...
1
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0answers
63 views

How to solve 6 equaitons with 5 unknowns in matrix form [closed]

I am having 6 homogeneous equations with 5 unknowns. can we use NullSpace to solve for unknowns or what else the correct code i can write to solve these equations. I have tried with 'NullSpace' ...
3
votes
3answers
134 views
1
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1answer
362 views

Why does Wolfram Alpha not return a solution to this problem involving Floor[]? [closed]

Wolfram Alpha did not find the solution $$x=\frac{8}{7} , y=7$$ to the equations below. Why? What can be done to expect more accurate results from Wolfram Alpha, in similar cases?
1
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2answers
159 views

Precision/AccuracyGoal in FindRoot don't work

I am trying to solve a system with two transcendental equations and an additional condition and it does not work the way I want it to. I am using this table with coefficients ...
0
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1answer
40 views
6
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1answer
217 views

Monitoring the progress of FindRoot during evaluation [closed]

I would like to know whether there is a way to monitor the evaluation of the norm of the error of FindRoot. Sometimes the evaluation of of this for a large system ...
2
votes
2answers
75 views

Return approximation error with FindRoot

I am solving a large system of equations. I would like to know to which extent the the solution that FindRoot returns to me is accurate: ...
1
vote
1answer
140 views

New to Mathematica - Finding 5 roots

I'm very new to Mathematica and I'm trying to find a way to find 5 roots for the following: xtan(x)=1 and sin^2(πx)-x^2*cos(πx)=x I feel that it's a simple solution but I'm having a hard time. ...
1
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0answers
94 views

what is the means of (0 -> 1) of series expansion [closed]

I use mathematica 8 to take a taylor expansion.In the Output, the expression (0->1) appears in the second term and all higher order term, and this expression is multiplied with other coefficient and ...
2
votes
1answer
88 views

Solve for a range of values

I am trying to solve the following eqn for Tco. The ultimate goal is to Plot Tco for zb values from 0 to 12. ...
2
votes
3answers
401 views

Solve an equation that include Gamma

I want to solve the following equation Solve[Gamma[1 + x]/Gamma[x - 1/2] + 1 == 0, x] I have answer x=-0.25, but I can not obtain this answer with Mathematica. ...
3
votes
1answer
136 views

Newton's Method Glitch

I wonder if you can help me with my program - it involves using Newton's Method but my main issue is getting a defined function to return a given value. Essentially, I want to get my function ...
2
votes
1answer
102 views

Solving a consistent overdetermined linear system

Not a duplicate question. I already tried all the Answers offered for this Question and they failed, so I believe this is a different problem with Solve[]. I have ...
-1
votes
1answer
68 views

When NSolve for X, Y, only output solution for X

I have an NSolve with two equations and two unknowns (X,Y). There is a unique solution. NSolve currently gives me the solution pair (X,Y). But I only want to read out one of the variables (say X). ...
0
votes
2answers
96 views

After NumberForm I cannot apply a Sine function. Why? [duplicate]

After NumberForm I cannot apply a Sine function. Why? This works: sol1 = x /. Solve[x^2 - 3 == 0, x] Sin[sol1] Output = $\{-Sin[\sqrt{3}],Sin[\sqrt{3}]\}$ Also ...
1
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3answers
348 views

Solve simple trig equation

I would like to solve this equation: $$-x\sin(x)=\cos(x)$$ But Solve in Mathematica doesn't work: This system cannot be solved with the methods available to ...
0
votes
1answer
128 views

Solve a function to find the optimum value of parameter in mathematica [duplicate]

I have a complicated function as shown It doesn't have a standard integration as far as I know. Now, numerical integration of the left hand side function over a set of points gives the right hand ...
2
votes
1answer
285 views

What is wrong with FindRoot?

I am trying to find a numerical solution to the following transcendental equation ...
0
votes
1answer
54 views

Strange Simultaneous Equations [closed]

Solve the simultaneous equations: 70-T=7a T-40=4a By multiplying both sides of the equations by a factor and shifting the terms I transformed them into the following form: -28a-4T=-280 ...
3
votes
0answers
122 views

NSolve doesn't work on an equation containing a numerical integral and constraints

I'm having trouble getting Mathematica to solve equations numerically. I know that its important to specify the type of variables for pattern testing (see e.g. here) but this doesn't seem to work. ...
1
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2answers
174 views

How to solve this two algebraic equation simultaneously for u and H ?(all real number)

I want to find the non-zero value of H when beta is changing(especially what value of beta when increasing will there be a non-zero H value). H is between [0,100]. This is actually the calculation ...
2
votes
1answer
77 views

2D plot using output from the other function

I would like to get 2D plot using output from the other function. FindInstance[0.5*x^2 + Cos[y + P] == 1, {x, y}, Reals] By changing values of P manually it gives ...
4
votes
3answers
165 views

My evaluation is taking a lot of time

I was evaluating the roots of a transcendental equation, when I noticed that Mathematica never finishes but stays in the running state. The following is the code that I was using: ...
4
votes
1answer
98 views

Points on discriminant variety?

I am trying to find a way in Mathematica to compute points on discriminant variety for modest size systems, but I couldn't find one. The system is something like: ...
1
vote
1answer
86 views

solving a non trivial equation system

I try to solve a 4 equations, 4 unknowns system. Here is my code ...
0
votes
1answer
101 views

Reduction of an Inequality in $\mathbb{C}$

Reduce[ Abs[-((4 p)/(-1 + Sqrt[1 + 4 p + 4 q])^2)] + Abs[-((4 q)/(-1 + Sqrt[1 + 4 p + 4 q])^2)] < 1 , Abs[p]] It is taking lot of time. It is running. Can ...
4
votes
1answer
115 views

Why doesn't NSolve work for this equality? Wildly incorrect solutions are given in certain cases

I am trying to write a function that solves for p in the following equation: PDF[BinomialDistribution[n, p], x] == op The ...
2
votes
1answer
64 views

RootReduce-Part of Solve

I have given the following expression in $M$ and $z$: \begin{equation} a = \frac{-4 M^2+M (-3 z-5)+\frac{1.1875 z}{\sqrt{\frac{0.015625 z}{M+1}-1.5625} \sqrt{\frac{0.765625 ...
4
votes
0answers
76 views

Method of characteristics, recursion formulas

I'm helping a friend out with a problem. He needs to plot out the solution to a water surge in a pipeline. I have all the parameters set and I've put the equations in Mathematica, but I can't get the ...
2
votes
1answer
120 views

How to solve coupled complex-valued equations faster and get simplified solution

I have six coupled equations. How to solve these equations symbolically faster in Mathematica. In these equations, variables p,q,x,y are ...
1
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2answers
173 views

Trying to solve a system of equation

I am trying to solve 3 equations 3 unknown system on Mathematica in order to get numerical results for my three variables x,y,z but the software is always on the ...
1
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2answers
71 views

Condition on Inside of Region

How do I handle boundary conditions present in the region. Mathematica complains about the condition v [1 , t ] == u [1,t]. The condition should be given to this ...
3
votes
1answer
60 views

Reduce return a strange result for solving a equation with radical

Reduce[1/Sqrt[x] == x + 1/(Sqrt[2] + Sqrt[3]), x] the output is unreadable and include the symbol Reduce`CADAlgVar[1].
0
votes
1answer
65 views

what am i missing? [closed]

An attempt to solve ...
4
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0answers
68 views

Reduce doesn't solve this equations with condition

Reduce[{4==Abs[-1+2 Cos[2A]+2 Cos[2B]+2 Cos[2(A+B)]]},{A,B},Reals] worked well, but ...
1
vote
0answers
27 views

Minimizing values of expressions dependent on more variables [closed]

I need to enforce seven expressions dependent on seven variables to be zero. However, the expressions are quite complicated and generaly I get a system of transcendental equations which only sometimes ...
19
votes
3answers
1k views

How to find numerically all roots of a function in a given range?

It is common that I search numerically for all zeros (roots) of a function in a given range. I have written two simple minded functions that perform this task, and I know of similar functions on this ...
0
votes
1answer
68 views

NDSolve does not satisfy initial conditions

For the problem I'm facing, I have three coupled diff eqns that I'm trying to solve ...
0
votes
2answers
221 views

How to solve a pair of coupled 2nd order equations using shooting method

I have a pair of equations for x[t] and y[t]. Both are 2nd order and they are coupled. Now say that I know the following ...
0
votes
0answers
66 views

Equations in a quadratic field

I would like to solve a system of equations in a quadratic field, meaning that each variable $x$ of my system can be written $a + b \sqrt{d}$, where $d$ is a fixed value. Suppose for example that I ...