Questions on the analytic and numeric equation solving functions of Mathematica (Solve, Reduce, NSolve, FindRoot, DSolve, RSolve, etc.).
5
votes
2answers
200 views
Find all the integer numbers $a$, $b$, $c$, $d$, $e$, $f$, $k$ to this equation have three integer different solutions?
How to choose all integer numbers $a$, $b$, $c$, $d$, $e$, $f$, $k$ belongs to interval $[-10,10]$ to the equation $$\sqrt[3]{a x + b} +\sqrt[3]{c x + d} + \sqrt[3]{e x + f} =k$$ has three integer ...
8
votes
0answers
325 views
Proving inequalities with Mathematica
Question summary: I would like to learn some tips and tricks on how to prove inequalities with Mathematica.
I'm studying various inequalities in triangle that have the form $R+ar + bs\geq 0$, where ...
7
votes
0answers
144 views
Creating and using an explicit piecewise function in a convenient way
I have a set of data points that define a function in the form
curvePts = {data1,data2,...}
where
...
6
votes
0answers
222 views
MMA implementation of Earth Movers Distance?
Has anyone implemented in MMA the Earth Mover's Distance (EMD)? A concept dating back to Monge 1871, used to compare histograms and images, e.g., the CIEDE2000 Color Difference algorithm. Yossi ...
5
votes
0answers
46 views
Faster way to perform SameQ[Reduce[…], Reduce[…]]
I'm have some expressions that I need to confirm the equality of. SameQ[Reduce[...], Reduce[...]] works like a charm for the more simple expressions, however when ...
5
votes
0answers
119 views
What Method options does FindInstance accept?
While answering Trouble getting FindInstance to return multiple results for certain constraints it became clear that for this problem FindInstance would be better ...
4
votes
0answers
164 views
Incompleteness of FindInstance
I've been playing around with Resolve and FindInstance. I know that Resolve should always ...
3
votes
0answers
118 views
FindRoot gives a wrong solution which obviously should not be there
I got stuck on FindRoot and I didn't see any similar problem posted, so let me explain what I am trying to do and what problem I meet here.
I try to find roots of a particular function, which in the ...
3
votes
0answers
69 views
Symbolic solution to ODE, pure InverseFunction not evaluated
I'm new to Mathematica and I don't understand why in the solution of the following ODE, the #1 in the pure function is not immediately replaced by the corresponding ...
3
votes
0answers
256 views
How can I solve this complicated custom function numerically?
I have a complicated function that calculates the total value of payments from an account into which deposits are made annually. I'd like to solve the function for a growth rate numerically, but ...
3
votes
0answers
99 views
RSolve not returning known solution
I have the following recurrence relationship for which I know the solution is given by a binomial distribution:
...
3
votes
0answers
364 views
Solving a system of nonlinear equations self-consistently
I am trying to solve a set of three non-linear equations in Mathematica. I need help with them. The Mathematica code (in plain text format) is attached below. If you copy & paste the code below ...
2
votes
0answers
61 views
Reducing exponential inequalities fails
I am quite stumped by this problem :
Reduce[ N^(x-y) <1 && N > 0 , x, Reals]
gives the expected result
...
2
votes
0answers
111 views
Nest for large value of n
I am working on a problem to find the Feigenbaum constant. In this problem I have to get $f^{2^n}(1/2)$ with $f(x) = kx(1-x)$. I use Nest to get $f^{2^n}(1/2)$ but ...
2
votes
0answers
75 views
Conditional statements in intial conditions?
This is potentially a daft question, but I thought I'd ask it; I have some material free to diffuse in a boundary between rn and ro; I've been able to get it working nicely for neumann type boundary ...
2
votes
0answers
89 views
differential equations with implicit functions
I have an ordinary differential equation that contains coefficient functions that depend implicitly on the independent variable via an algebraic equation. I am trying to go ahead and use NSolve to ...
2
votes
0answers
138 views
Solving $k\log(n) - k\log(k) \leq u$
How can I persuade Mathematica to help me find solutions to the inequality
$k\ln(n) - k\ln(k) \leq u$ over the reals, assuming $u \geq n \geq k \geq 1$.
When I evaluate
...
2
votes
0answers
107 views
Am I entering this 2-variable recurrence correctly?
I'm trying to solve this recurrence with two variables.
...
2
votes
0answers
139 views
FindRoot - Speed and errors
I am using FindRoot[] to solve a complicated equation. It seems I get the correct answer even though I get errors about an ...
2
votes
0answers
174 views
Numerically/Analytically Solving a System of Equations
I have $6$ functions $f_i(x,y,z)$, $(i = 1, \ldots, 6)$ in three variables $x,y,z$, and I would like to find a simultaneous instance of these variables, say $(x_0, y_0, z_0)$, such that $f_i(x_0, y_0, ...
1
vote
0answers
55 views
Bounds on random number
I have a Markov Chain Monte Carlo code that uses a chi squared function to fit some data.
I am running into an issue now with getting unrealistic values for some of the free parameters
in the code. ...
1
vote
0answers
83 views
I can't solve this set of equations
I am having trouble solving a set of equations in mathematica. I do not get any errors, but i don't get any answers as well.
I have some restrictions on my parameters and variables in the equations ...
1
vote
0answers
73 views
Why is FindRoot initial value far from the specified one?
I am trying to numerically find the root of a function that looks a bit like: 1/x - (SchurDecomposition[A[x]][[2]])[[1]], where ...
1
vote
0answers
70 views
Solving for vector elements in a function to which the vectors are not passed explicitly
I want to define a function which takes in two integers (indicating the lengths of 2 vectors), and solves a simple set of expressions at a set of points to find all the values in both the vectors.
so ...
1
vote
0answers
124 views
NDSolve equations contain solution from solving cubic equations
I'm having trouble using NDSolve to solve equations that were obtained from solving cubic equations.
In my problem, I first obtained 6 functions (ca1, ...
1
vote
0answers
94 views
Automatic inverse for Lambert’s Azimuthal Equal-Area Projection
I’m interested in finding closed-form inverses for map projection equations in general (of course, this is not always possible). I’m hoping Mathematica can help me with some of the trickier ones.
As ...
1
vote
0answers
132 views
Does Solve give every solution?
When I run the following:
Solve[{
ac == anc, ac == acn, ac == ancn,
acn == anc, acn == ancn,
anc == ancn,
q1 + q2 + q3 + q4 == 1
}, {q1, q2, q3, q4}
]
I ...
1
vote
0answers
255 views
Calculating the mean curvature of a surface - suggestions
I am attempting to calculate the mean curvature [1, 2] of a surface defined by a function of x and y.
My function is rather ...
1
vote
0answers
77 views
Symbolic FindInstance
I'm wondering if there is any way of doing something like the following:
FindInstance[x < y, {x}, Reals] and getting, as a possible return value, ...
1
vote
0answers
89 views
Skip one step of the loop if there is NIntegrate::eincr: message
is there possibility to skip one step of the loop if in this step there appear error like NIntegrate::eincr:? For example: when I use "do" loop and when one of the step is evaluating I would like to ...
1
vote
0answers
276 views
Using constraints in Solve[]
I'm not sure if the title fits.
I'm basically just looking for a way to define a value and constrain it to $[a,b]$ when I use Solve later.
More specifically, I ...
0
votes
0answers
19 views
How can i get the solution of complicated equation?
This is the equation about zeta. NSolve[equation] could not solve this equation. (I think it is too complex to solve by NSolve.)
I want to know how can i solve this equation such a complicated ...
0
votes
0answers
44 views
Collect and factor equations with certain terms
Collect user defined terms from a symbolic algebraic expression
...
0
votes
0answers
80 views
Solve equations real and imaginary part separately
For my system of equations, the procedure described in Solving complex equations of using Reduce works no more. How can I separate the real and imaginary part of ...
0
votes
0answers
77 views
Simultaneous Equation Solving Under Nonnegative and Bounding Conditions
I have nonlinear equations to solve parametrically;
...
0
votes
0answers
51 views
DSolve::overdet for system of linear PDEs
I would like to resolve symbolically the following equation:
...
0
votes
0answers
77 views
Defining and Solving Systems of Equations Using Matrix Tables
I've defined a system of equations, but I been unable to get Mathematica to solve for the individual variables created by matrix tables.
...
0
votes
0answers
51 views
Finding all roots of the system of two complex equations
I need to find all roots for the system of two complex equations. Obviously I can rewrite them as 4 real however problem remains. I have looked through routines connected with using ContourPlot ...
0
votes
0answers
44 views
Solving ODEs produces error NDSolve::nrnum1
I'm a new member but I have been reading the great answers here for sometime now.
I am trying to solve a system of ODEs for various values of a parameter epsilon, using a slider. I am using ...
0
votes
0answers
78 views
“Nesting” FindInstance and FindRoot
The problem I face involves three constrained optimization problems (which i will call B,R and F) which interact. The optimization problem F is solved "after" (in terms of the model behind the ...
0
votes
0answers
184 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
votes
0answers
192 views
Vertices of the region defined by inequalities
I have a set of 8 inequalities in two variables $X$ and $Y$. In Mathematica, using the command Reduce I find the solution. The solution plotted with ...
0
votes
0answers
310 views
Solving system of non-linear equations
I'm trying to plot the concentration of chemical reaction products (PL,PL,LPL) vs. molar ratio of initial components concentration (r). All concentrations are positive, rational and could not exceed ...
0
votes
0answers
83 views
FindRoot is only passing two variables
When I run the code:
q0 = FindRoot[findarea[ch, rh, ah, lineh, intersecth, q][[1 ;; 2]] == ah[[1 ;; 2]]*r3^2,
{q, q0}][[1, 2]];
...
0
votes
0answers
276 views
Reduce/NSolve cannot solve a constraint problem?
I am trying to solve the following problem:
Minimize Integral[ (y''[x]+10)^2,x]
Where y''[x]+a*y'[x]+y[x] = 0, and the initial conditions for the DE are
...
0
votes
0answers
269 views
FindMinimum , FindRoot Not working. What am I doing wrong?
I have a matrix that depends on a parameter,call it $\kappa$, and to find the numerical value for $\kappa$ I'm trying to solve det(A($\kappa$) = 0. Of course this is hard to do symbolically, and even ...
-1
votes
0answers
40 views
Evaluating the different calculations
I am a new user. I wonder that either there is possible to evalute different calculations at the same time in Mathematica or not? Can i share the kernels for different calculation at same time?
