Questions on the analytic and numeric equation solving functions of Mathematica (Solve, Reduce, NSolve, FindRoot, DSolve, RSolve, etc.).
0
votes
1answer
62 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}]
...
1
vote
1answer
62 views
Calibrating Precision in calculations
As the title says, I encounter an irritating problem which has to do with the accuracy or the precision used in the calculations. To be more specific, I have the following code:
...
1
vote
1answer
99 views
Forcing evaluation of ArgMax
How to force evaluation of ArgMax before its output gets used in Solve?
Background: I'm trying to solve for the Nash ...
0
votes
1answer
97 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 ...
2
votes
1answer
141 views
Solving an equation involving a determinant
I have a matrix which doesn't include numerical values. There are four variables in it. It is defined by
...
-3
votes
1answer
202 views
Why can't Mathematica solve these non-linear equations? [closed]
$l_{2}$ and $\theta$ are the variables. All other parameters are constants. I need to find $l_{2}$ and $\theta$ in terms of these constants.
$\frac{\mu_{0}\sin(\theta-\theta_{0})}{\sqrt{l_{2}^2 ...
1
vote
0answers
71 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 ...
4
votes
1answer
141 views
Can mathematica resolve this equation?
Obviously，the equation $x^2-3 y^2=2 z^2$ doesn't have positive integer solutions.
I tried
...
3
votes
1answer
88 views
How can I get a single solution to a set of inequality constraints?
I have a set of constraints to which I require integer solutions. However, instead of needing all possible integer solutions (as obtained by using ...
4
votes
2answers
213 views
All possible solutions to the Matrix Equation (free variables appearing)
I am attempting to solve a system of linear equations using LinearSolve[] . In my case, the number of unknowns are more than constraints. I learnt that LinearSolve ...
1
vote
1answer
133 views
Stop Mathematica from giving imaginary solutions
I have the following equation:
$$D=\frac{1}{64} \pi A ^3 B \sin \left(C\right)-\frac{1}{2} \pi A B \sin \left(C\right)$$
which I want to solve for $A$. The equation is cubic in $A$ so this should ...
1
vote
1answer
101 views
2
votes
1answer
164 views
How to solve equations self-consistently
I want to solve the following equation self-consistently. So,
H.u = e.u
{{1, d}, {d, 1}}.{u1, u2} = e.{u1, u2}
I guess an initial value for ...
1
vote
1answer
128 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 I ...
0
votes
1answer
73 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 ...
4
votes
2answers
143 views
Finding all/most roots of a discontinuous function more consistently?
I have the equation:
f[x_]:=α Tan[α*a] - Sqrt[c - α^2]
and ideally I want to find all of its positive zeros, given a and c, with variable alpha. The problem is ...
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, ...
2
votes
1answer
94 views
How to transform an expression using algebraical instead of pattern rules [duplicate]
I would like to transform rules algebraically. A very simple example would be: -
k^2 - 2 k x + x^2 /. {2*k -> 1}
This transforms to: -
$$k^2-2 k x+x^2$$
...
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 ...
3
votes
2answers
90 views
Find condition under which variables fall away
I have a somewhat lengthy expression, looking like
expr = 1 + x + b + Pi + 2*a
Is there some way of generating a relationship between ...
4
votes
2answers
327 views
How do I solve N simultaneous equations for N variables?
I have a function:
f[x_] := x + 31 x^3 + 5 x^25
Which I want to find an expansion for:
...
7
votes
2answers
230 views
Finding all points of period n in an iterated map
I'm trying to implement an algorithm of Jenkinson and Pollicott to calculate the Hausdorff dimension of a Julia set for the map $f_c : z\mapsto z^2 + c$. It's described on page 40 of their paper, ...
2
votes
3answers
239 views
Symbolic derivative of $n$-term product
I want to determine the relationship that must exist between the $x_i$ and $y_i$ such that
$$
\frac{\partial}{\partial\theta} \prod_{i=1}^n \frac{f(x_i,\theta)}{f(y_i,\theta)} = 0,
$$
where
$$
...
8
votes
2answers
248 views
Find the parameter values satisfying conditions for all roots of an equation
Hi I'm very new at Mathematica.
My real problems concerns a much more difficult equation with many parameters, but I want to check that the method is good, so I made up a test equation.
My test ...
3
votes
1answer
148 views
What properties make this equation difficult to symbolically solve?
I tried to solve the following equation with Mathematica's solve:
Solve[K*(2*Tan[L/2*Sqrt[P/(EI)]]-L*Sqrt[P/(EI)])+4*P*Sqrt[P/(EI)] == 0, P]
It gave the ...
0
votes
1answer
114 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). ...
0
votes
2answers
96 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 $m$
...
14
votes
1answer
418 views
Bug in Solve (Mathematica 9)
Just came across the strangest bug under both Mathematica 9.0.0 and 9.0.1. If one enters:
Solve[m == p Sin[x] && -Pi/2 < x < Pi/2, x]
... then ...
0
votes
1answer
159 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 ...
6
votes
4answers
545 views
Why does Mathematica struggle with solving this equation?
Consider the evaluation of the following expression
In[20]:= Reduce[1000*1.0609^t == 1500, t]
During evaluation of In[20]:= Reduce::ratnz: Reduce was unable ...
-1
votes
1answer
99 views
Solving an equation for asymptotic dependence of the solution on a coefficient
I have an equation I want to solve, so I entered the following into Mathematica.
(x^(17/6))/(a^(17/6)) - (x^2)/a -1 == 0
where I assume $a>>1$ and $x$ is ...
3
votes
2answers
154 views
Eliminate several variables between five Conic_section equations
I want to eliminate x1, x2, y1, y2 between these 5 equations.
I tried
...
2
votes
2answers
200 views
Solving set of non-linear simultaneous equations gives PolynomialGCD::lgrexp error - what next?
I'm trying to solve a set of six simultaneous non-linear equations to get a numerical answer using NSolve:
...
0
votes
1answer
57 views
Create set of equations by replacing constant values
Say I have an equation:
eq = ax + by + c == 0
and I want to run NSolve on a set of equations of this form, for example:
...
0
votes
0answers
94 views
using FindRoot in for loop [closed]
I am fairly new to Mathematica so I am not really familiar with all the "kinks" in its syntax (a matlab lover).
I am trying to run this:
...
3
votes
2answers
178 views
How can I solve an equation with symbolic coefficients?
I want to try to solve the following
a x^(17/6) - b x^2 - 1 == 0
where a and b are ...
2
votes
2answers
88 views
Why can't FindInstance find a solution to this equation?
FindInstance[680 == 1/3 2^m (-1 + 4^v), {m, v}, Integers]
FindInstance seems to be unable to find the integer solution $ {m = ...
2
votes
0answers
107 views
Am I entering this 2-variable recurrence correctly?
I'm trying to solve this recurrence with two variables.
...
0
votes
1answer
124 views
2
votes
3answers
261 views
Using DSolve to solve for x[t,parameter]
I'm trying to solve an ODE with two independent variables (a cannon firing from a cliff incorporating wind resistance dependent on velocity). I've tried the following for the x-component:
...
0
votes
3answers
446 views
Solving cubic equation for real roots
I'm looking to solve the following cubic equation for x:
$\beta\, x^3 - \gamma \,x = c$. I have plugged in some sample values ($\beta = 2$, $\gamma = 5$ and $c = 2$). When I try to solve this ...
7
votes
3answers
256 views
How do I make Reduce yield all solutions explicitly?
Say I want to do the following:
Reduce[ x+y+z==1, {x,y,z}, Modulus -> 7 ]
then I get a solution with parameters, C[1] :
...
2
votes
1answer
108 views
How can I get the general term of this recurrence equations?
Following is the recurrence relation:
a[1] = 1;
a[n_] := a[n - a[n - 1]] + 1
Array[a, 28]
I tried to use RSolve, but it ...
0
votes
0answers
185 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, ...
7
votes
3answers
900 views
Finding unit tangent, normal, and binormal vectors for a given r(t)
For my Calc III class, I need to find $T(t), N(t)$, and $B(t)$ for $t=1, 2$, and $-1$, given $r(t)=\{t,t^2,t^3\}$.
I've got Mathematica, but I've never used it before and I'm not sure how to coerce ...
1
vote
1answer
96 views
Finding parameters for first positive root of solution to differential equation to be equal to a desired value
I have a differential equation with parameters. The objective is to vary the parameters such that the first positive root of the solution is equal to a desired value ...
1
vote
2answers
131 views
Is there a better way to get the eight points of intersection?
I want to get the eight points of intersection from the equations 2 Abs[x] + Abs[y] == 1 and Abs[x] + 2 Abs[y] == 1. To solve ...
0
votes
1answer
167 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 ...
4
votes
2answers
134 views
How can I eliminate equivalent equations from a list?
I want to find the numbers $a$, $b$, $c$, $d$ of the plane $ax + by +cz +d = 0$ which make the distance from the point $M(1,2,3)$ to the plane equal to 2. I tried
...
2
votes
1answer
407 views
NSolve: Mathematica 9 issue
In Mathematica 8 the following expression evaluates and returns a result in terms of InverseFunction:
...
