Tagged Questions

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

223 views

Tracking FindRoot errors in NestWhileList and Table

I'm solving many systems of two equations by varying the initial parameters. I'm running FindRoot in a NestWhileList where the ...
787 views

wrong use of _?NumberQ?

I am having trouble with a numerical exercise. Here's a simplified version of my problem. I define two functions to find the solution to two constrained maximization problems: ...
81 views

Solve equation for a function as solution

I need to solve the following function: $$h(z) = \sum^{40}_{k=0} \frac{k \, p(k)}{z- k \, h(z)}$$ where $p(k)$ is a probability distribution (in this case binomial with n = 40). Note that $h(z)$ is ...
57 views

How can I choose the coeffcients so that the givent system of equations has four integer solutions?

Consider the system of equations with unknown are $(x,y)$. $$\begin{cases} a_1x^2+b_1y^2 + c_1xy+d_1x + e_1y+f_1=0,\\ a_2x^2+b_2y^2 + c_2xy+d_2x + e_2y+f_2=0. \end{cases}$$ I want to find the ...
94 views

How to efficiently find only the rational roots of a rational complex polynomial?

I need to find all the rational roots of a bunch of high-order polynomials with rational complex coefficients. Is there an efficient way to do this? My best effort on an example polynomial: ...
180 views

How to tell Solve[] to satisfy as many constraints as it can?

Is there any way to tell Solve (or something similar) to return values for variables that solved as many constraints as it happened to satisfy? Edit: I had ...
67 views

Reduce is not giving answers, only verifies it's true

I'm trying to find a range for {q1,q2} with the conditions listed such that U1R >= U1S ...
68 views

Finding inconsistencies in a system of equations

I am a rookie in Mathematica and apologize in advance. Here is my question: Are there any tools, built in the program, of detecting inconsistency in a nonlinear system of equations? Whilst finding ...
98 views

Unable to solve equation for a variable by any method

I am looking to solve for the value of r when the derivative of the expression ...
72 views

SolveAlways 'never' completes

After allowing Mathematica to run on ...
105 views

Proof or find counterexample to inequality (in three vars)

I'm trying to show \begin{eqnarray*} \left(\frac{1-q^r}{1-q^n}\right)^{\frac{1}{n-r}} \left(\frac{q^n \log (q)}{\left(1-q^n\right) (n-r)}-\frac{\log \left(\frac{1-q^r}{1-q^n}\right)}{(n-r)^2}\right)&...
118 views

Solve Differential Equations with Boundary Condition at Variable Point

I have a set of differential equations: ...
191 views

How do I solve for a variable inside a sum but independent of the summation index?

How would I go about solving the following for c? Solve[0 == Sum[(t[i]*m[i] - c*t[i]^2)/s[i]^2, {i, 1, n}], c, Reals] I get ...
108 views

How can I solve my easy system of equations?

I am new to Mathematica and am afraid this is a silly question. I have this very easy substitution, it has three equations on three unknowns {w1, l1, t1}. I want to ...
171 views

Numerical root-finding: Find leftmost root in a domain

This is surely a duplicate, but I cannot seem to find a similar question. I use NDSolve to find an InterpolatingFunction y[t] ...
315 views

Solving a large system of nonlinear equations

I have a system of 80 nonlinear equations with 64 variables to solve in Mathematica but it takes a lot of time (about two hours) and then it return "no more memory available" knowing that I have 8GB ...
137 views

Solving a system of generated equations?

I would like to generate a function in the following form, where the number of terms can be specified arbitrarily: ...
77 views

Finding linearly independent combination of vectors with a certain symmetry property

I have two linearly independent vectors $v_1$ and $v_2$. Is there a way for me using Mathematica to find two linear combinations $w_1$ and $w_2$ such that: $w_1$ and $w_2$ are linearly independent. ...
102 views

Why do two roots of my equation disappear when I give numerical values to two parameters?

Consider the equation ...
293 views