Questions tagged [equation-solving]
Questions on the analytic and numerical equation solving functions of Mathematica (Solve, Reduce, NSolve, FindRoot, DSolve, RSolve, etc.).
4,575
questions
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12 views
What class order should I use to study calculus?
I would like to know how I should go about studying calculus, and in what order should I take the classes. I have searched tirelessly for answers and I am still confused.
Here is what I have gathered ...
9
votes
1answer
140 views
How can I find a functional square root in Mathematica?
A functional square root of a function $g$ is another function $f$ such that $g=f\circ f$. According to that article, there is a systematic approach to finding a functional square root that involves ...
0
votes
0answers
61 views
How to eliminate the list case by `Eliminate` function
It is known that line L1: $\frac{x-a_{2}}{a_{1}}=\frac{y-b_{2}}{b_{1}}=\frac{z-c_{2}}{c_{1}}$ and line L2: $\frac{x-a_{3}}{a_{2}}=\frac{y-b_{3}}{b_{2}}=\frac{z-c_{3}}{c_{2}}$ intersect at a point.
Now ...
0
votes
1answer
34 views
How to define a function to decouple equations and transform them into standard form
I want to convert this expression($\frac{x-a 2}{a 1}=\frac{y-b 2}{b 1}=\frac{z-c 2}{c 1}$) of the linear equation into a standard form $\left\{\begin{matrix}
\text { b1 } * x-a 1 * y=a 2 * b 1-a 1 * ...
0
votes
0answers
25 views
Reduce does not solve a system of equations
I am trying to solve a system of 7 equations and 7 unknowns given a set of assuptions. I am only interested in obtaining V3 as a function of the exogenous parameters.
I am using the following code:
<...
1
vote
0answers
42 views
How can I convert a list of rules into a list of equations? [closed]
How can I convert a list of solutions to a list of equations? For example, say I have:
sol = {{a->1},{b->2}}
and I would like to change it to
...
0
votes
1answer
52 views
Solve with > instead of == [duplicate]
I want to solve a complicated equation with the sign > instead of ==. However, mathematica Solve function is not defined for >. Can somebody tell me how to do it?
Code example:
...
-1
votes
0answers
30 views
Solve with Trig cycled variables
eqn={p2 == u^2 + v^2 - 2 u v csal, q2 == v^2 + w^2 - 2 v w csbt, r2 == w^2 + u^2 - 2 w u csgm}
Solve[eqn, {u,v,w}]
Hangs indefinite. How to Solve... using ...
3
votes
2answers
81 views
Solve system of equations with integration over regions
I want to solve the following problem in Mathematica:
Assume that $\lambda_2=-\frac{1}{2}+ r+\frac{1}{1+r}- r^2\log\frac{1+r}{r}$, $v\in[0,1]$ and $\theta\in[0,1]$. For pre-specified values of $k,r>...
1
vote
0answers
56 views
Groebner Basis for Functions
We can use Reduce to solve the following
Reduce[1 - Sqrt[a^(-1)] + Sqrt[2]*Sqrt[(a + a^2)^(-1)] - Sqrt[2 - 2/(1 + a)] == -1 + Sqrt[2], a, Reals]
We can also do ...
2
votes
2answers
409 views
Why is Mathematica taking so long to solve this equation?
I was trying to solve a polarization problem where I needed to solve this transcendental equation.
NSolve[(Cos[\[Pi]/n])^(2 n) == 0.90, n]
I don't know why but ...
3
votes
1answer
74 views
Plotting in for loop
I am having some problem while plotting the data being generated in for loop
My aim is to plot the result of for loop while it is solving the equation for each value of w,i.e. plot between w and x
...
6
votes
2answers
382 views
Finding the intersection(s) of a 3D parametric surface and a line
I have some 3D parametric curve par and some line line.
I want to find parameters u,v and t for the intersection points of par and line.
I tried to do that with NSolve in many different ways and ...
0
votes
0answers
63 views
4
votes
2answers
139 views
0
votes
1answer
61 views
How o use singular value decomposition function to find the natural frequency and mode shapes
I have a matrix R which is having a dependency on Ļ, I am interested in finding the natural frequency and mode shapes of this matrix using SVD how to do this?. The regular way is to take the ...
2
votes
2answers
150 views
How to solve a nonlinear second order ODE
I want to solve this equation
y''[x] + a + b y[x] + c y[x]^2 == 0, y[ā] == 0, y'[ā] == 0
where a, ...
0
votes
1answer
108 views
How to solve a differential equation involving LaplaceTransform?
currently I'm working on a problem in which I need to solve an equation of the following form:
$$\mathcal{L}\left[\frac{\partial f(x,t) }{\partial x} + \frac{\partial f(x,t)}{\partial t}\right] = \...
0
votes
0answers
33 views
Exiting CrossSlidingDiscontinuity in NDSolve to follow equilibrium curve
I am trying to figure out how to get the solution curve to an NDSolve to slide along once it reaches a boundary and then to exit the ...
1
vote
0answers
41 views
Solving a cubic equation in mathematica
I am trying to solve a cubic equation using Mathematica of a rather complicated expression say $f(r,\beta,\theta)$ , and in terms of $r$ the maximum degree term that appears is of degree $3$ so I ...
2
votes
2answers
114 views
How to solve Nonlinear coupled ODEs using DSolve
I cannot solve such a system of coupled ODEs in MMA 12.1 using DSolve.
i.e. output is equal to the input equations ... (see the attached figure)
Here, each solution is labeled according to the name of ...
1
vote
1answer
48 views
Says that my variable is 45 degrees and not valid [closed]
I tried to run Solve[2x+1==6,x] and it has given me an error saying 45 degrees is not a valid variable. How do I fix this?
1
vote
1answer
69 views
How to fix the Y-axis and normalize density?
I want to plot a density curve but when I draw the y-axis not getting to 1 (as normalized)
...
0
votes
1answer
57 views
How to do Interpolation to this function after given b this values
\[Chi][b_] := (Z/k)*NIntegrate[Subscript[f, pp1][q]*Subscript[F, pp1][q]*BesselJ[0, q*b]*q, {q, 0, b}];
bList = Table[b, {b, 0, 5.1 , 0.05}]
where:
Z = 6;
k=1....
1
vote
1answer
35 views
How to find the roots of a transcendental equation that depends on Bessel functions? [duplicate]
I am very new in wolfram mathematica, so i am having trouble in trying to find the roots for this
transcendental equation. I am looking for roots of m. Acctually the first non zero value for m. Here J ...
2
votes
1answer
112 views
4
votes
1answer
227 views
How to solve the differential equation
I need to solve the differential equation
DSolve[{(1-x)y''[x]==1/5 \[Sqrt](1+y'[x]^2),y[0]==0,y'[0]==0},y[x],x]
but the result given seems to be incorrect and ...
0
votes
0answers
16 views
How to solve an equation by substituting possible solutions? [duplicate]
I wish to solve this equation for kappa, given a certain set of parameters (m and beta):
...
0
votes
0answers
51 views
Help me factor this equation
I have the following equation:
$$\frac{2\left(a A_3 r + \frac{1}{2} r^2 a'^2 \right)}{a^2 r^2}=\frac{8 G \pi \rho}{3}-\frac{c^2 k}{a^2}$$
...
1
vote
1answer
139 views
Implementation of the general solution of Abel differential equation of the second kind in Mathematica
Introduction
An Abel equation of the second kind in its canonical form is writen as
$$y(x)y'(x)-y(x)=f(x)\quad (6)$$
for arbitrary $f(x)$. Despite the fact that this equation has general solutions 1 ...
0
votes
1answer
81 views
Mathematica does not solve system of equations
I am trying to solve a system of 7 equations and 7 unknowns given a set of assuptions. I am only interested in obtaining V1 as a function of the exogenous parameters.
I am using the following code:
<...
1
vote
0answers
39 views
How to find solutions of a two-variable equation with discrete domains?
I have a two-variable function f[x_, y_] == 0, with a discrete domain for each variable, $x=\{1.5,\; 2.5,\; 3.5,\;4.5,\;5.5,\;\text{...},\infty \}$ and $y=\{0.1,\;...
0
votes
1answer
54 views
Root finding: Is there no bisection method root finder?
I am trying to find a root to an equation f[k,...]==0 numerically, where k is the variable I am solving for. Using both NSove as ...
0
votes
0answers
99 views
Is it possible to solve this equation analytically?
I have this equation, and I want to find an exact solution for $x$ in terms of $y$. I mean I want to obtain something like $x=f(y)$. Is it possible to solve this equation analytically by Mathematica?
<...
2
votes
2answers
63 views
5
votes
1answer
131 views
How can I reduce timing to solve this equation?
I am tring to solve equation $$\frac{2 \log (x y+2021)}{\log
(2)}+4^{x+1}=2^{x y+2022}+\frac{2
\log (2 x+1)}{\log (2)},$$
where $x$, $y$ are integer numbers.
I tried
...
1
vote
2answers
43 views
Evaluate with numbers from list
This code works:
x=2
y/.Solve[y==x^2]
Out[138]= 2
Out[139]= {4}
So above I put number in variable x and getting the result of ...
0
votes
4answers
121 views
Is it possible to get a symbolic or numeric relation when solving a transcendental equation? [closed]
Here is the code.
Solve[(1 - E^x + (3 x^2)/2)/(2 x) == a, x, Reals]
Unfortunately, Mathematica told me that this system cannot be solved with the methods ...
2
votes
2answers
88 views
How can I solve $\coth (2 x )=x $? [duplicate]
I have this equation $$\coth (2 x )=x $$ and I want to solve it to find $x$. The methods Solve and Reduce do not work.
Coth[2 x] == x
0
votes
0answers
38 views
How to deal with unknown variables in NSolve?
I am trying to solve these equations by using NSolve and want to plot $p1^{2}+p2^{2}$ v/s P0. But there is some problem, it is showing running... but not showing any error. I don't know where I am ...
1
vote
1answer
69 views
Why mathematica does not solve the equation $x\left \lfloor x \right \rfloor=10$ for $x$?
The equation $x\left \lfloor x \right \rfloor=10$ has a real solution, which is $x=\frac{10}{3}$.
But when I type
Solve[x*Floor[x] == 10, x]
a message comes: "...
6
votes
1answer
153 views
How to solve system of PDE's with complicated initial and boundary conditions
I am trying to solve the Cavity problem given in Paper by Mansour et al. with a physical model .
System of PDE and B.C are .
How can I impose boundary conditions like this?
Code
...
0
votes
1answer
38 views
how to solve a quadratic diophanic equation on integers and obtain various results
This quadratic di equation has more results, as it came to them.
I can only think of this
FindInstance[(4 p + 3 q - 2) (p - 1) == (6 p + 2 q) q, {p, q}, Integers]
...
1
vote
1answer
39 views
Find the condition under which an inequality holds
I've got an inequality of 8 non-negative parameters (arising from a 5x5 matrix) and would like to find a condition under which my inequality holds. The condition would be an inequality too of these ...
0
votes
1answer
30 views
why mathematica Holds the Solve on the set of equations in the diagonal a matrix?
Say I have a simple function
F[x_, y_, z_, r_, a_, b_, c_, d_] := (1 - a + b - (b/3) (c x + d (y + z + r))) x
And I want to solve the set of equations given by:
<...
2
votes
1answer
52 views
Find non-unique Hermitian solution to pair of matrix equations
This is a continuation of my previous question here, but I previously did not fully specify some of the restrictions on the matrices and so the solutions posted there were not that helpful.
I'm ...
3
votes
1answer
104 views
two tier compound interest problem
I am trying to make sense of how mortgage repayment figures are calculated for two tier mortgages, where you fix your interest rate for a certain period and after that period, you fall back to the SVR ...
1
vote
1answer
31 views
Get Solution range of NSolve
I have a numerical solution and when I solve it with NSolve, and substitue the results in an expression, I get something like:
1 + x + x^2 if 0 < x< 10
I ...
3
votes
1answer
75 views
Solving Inequalities using Mathematica
How can I solve this inequality using Mathematica?
Sqrt[B^2 + J^2] Cosh[(2 J)/T ] < J Sinh[ (2 Sqrt[B^2 + J^2])/T]
where T, J, and B are reals and they are >...
2
votes
3answers
80 views
How to solve these complex equations for plot?
I am trying to Plot this code but it is not showing any plot. I want a bistable type plot between "NL" and "P0" and there are six equations and six unknowns. The code is given ...
