Questions tagged [warning-messages]
The warning-messages tag has no usage guidance.
1,161
questions
1
vote
1answer
47 views
Error on DSolve
I've been trying to solve this initial value problem using 'DSolve[]':
$$
\frac{dy}{dt}=1+t\space \sin(t\space y),\quad y(0)=0, \quad t=[0,2]
$$
...
1
vote
1answer
73 views
0
votes
0answers
54 views
Getting warnings when I try to numerically solve a diffusion equation [closed]
I am trying to solve the diferential equation for diffusion:
$\qquad dt(u)=A\,dx(u^m\,dx(u))$,
where $m$ is the difussion coefficient. In this case, I am trying to make $m$ a function of $x$, and ...
2
votes
5answers
164 views
Finding polynomial coefficients returns Tag Plus is Protected
I'm trying to find the coefficients of a polynomial $P(x)$. Please see following equation.
$$P(x+2)+P(x-2)=2x+8$$
CoefficientList[P(x+2)+P(x-2)=2x+8,P(x)]
However ...
1
vote
0answers
29 views
Problem initializing xTensor package
I am using Mathematica 12.2 on Windows 10 and I am using the xTensor package for my tensor calculations.
However, since today, I cannot run the xTensor package. I get the following error. Can anybody ...
3
votes
1answer
58 views
Too small to represent and Chop in inaccessible algorithm
Overview
I want to apply a specified Chop function to every step in an function call in Mathematica (in my case LegendreP), ...
2
votes
0answers
88 views
Trying to solve a PDE — getting warnings I don't understand
Consider the partial differential equation
...
0
votes
1answer
70 views
List Plot Error [closed]
I've produced this simulation of a superhetrodyne radio receiver. I'm pretty sure it's solid for the most part but I'm getting a list plot error.
ListPlot::lpn: {{{1.,0.},{2.,0.00104953},{3.,0....
1
vote
0answers
40 views
NDSolve - interpolation or machine precision problem
For the following equations;
$$\begin{align}
\frac{\partial \text{NN}(t)}{\partial t}&=-\frac{(c \times\text{Sigma})}{\pi\times L\times \text{Omega}^2} \text{NN}(t) \times\text{Phi}(t)-\frac{\...
0
votes
1answer
92 views
When I define a Piecewise function containing a solution to a partial differential equation, the function cannot be evaluated numerically
I need to find an integral, in which there is a function
YO [x_] =
Sum[E^(((I h PI)/(λ f))x^2) Subscript[Y, h][x, z = 13.5], {h, - 5, - 1}] /. s
where ...
3
votes
0answers
48 views
Mathematica gives $RecursionLimit to every single input [closed]
I have been using Mathematica Cloud for about 3 months. About twice a month I encounter a strange and perplexing error that I have, until now, overlooked as an immovable bug. Every function I input, ...
5
votes
1answer
110 views
'Block' with 'Compile' gives an error
Here is a minimal example to the problem I face when using Compile with Block:
...
2
votes
1answer
41 views
Getting error Solve::units [closed]
I'm trying to solve the following formula for i, given values for all other variables. There are two equations, the first one is a formula to show the transit ...
6
votes
2answers
689 views
What is the reason for failing to solve the following equation?
I have a simple differential equation
$$
\frac{df(T)}{dT} = g(T)(f(T)-f_{\text{eq}}(T)),
$$
where $g,f_{\text{eq}}$ are some smooth functions, and $T$ is an analog of time, but the evolution ...
1
vote
1answer
86 views
Find minimum of a function defined via NIntegrate [closed]
I need to find the minimum of a function f(t) = int g(t,x) dx over [0,1].
I used
g[t_, x_] := *huge expression*
f[t_?NumericQ] := NIntegrate[g[t, x], {x, -1, 1}]
...
4
votes
1answer
138 views
Step size is effectively zero
I've been trying to solve Bodewadt flow equations which is a system of differential equations.
$$\begin{align*}
F^2 - G^2 + HF' - F'' + 1 &= 0 \\
2GF + HG'-G'' &= 0 \\
2F + H' &= 0
\end{...
0
votes
0answers
51 views
How to solve this linear complementarity problem with NDSolve or other functions? The arguments should be ordered consistently
I want to find a numerical solution of $\omega(t,q)$, where $t\in[0,T]$ and $q\in[0,N]$. $q_t$ is a determinstic w.r.t $t$, other unmentioned parameters can be fullfilled or given by the user.
I met ...
4
votes
1answer
74 views
Result is correct, but LinearProgramming spits out lpnn warning in RegionPlot
Sorry if this is a newbie question. I wrote a function to decide if a given vector is in the convex hull of another set of vectors using linear programming.
...
1
vote
2answers
102 views
What makes a system be differential-algebraic equations?
I am trying to solve the equations in the following way:
...
0
votes
0answers
25 views
How to avoid machine underflow for plotting and integrating?
I am trying to integrate the following integrand, which I have plotted:
...
0
votes
1answer
55 views
“ Unable to find initial conditions that satisfy the residual function within specified tolerances”
I know that there are similar questions on stack exchange. However, I am relatively new to mathematica, so I couldn't really understand the answers. Sorry.
Here's my code:
...
0
votes
1answer
59 views
Error message when solving simultaneous differential equations
I am trying to solve the following set of differential equations to obtain $\phi[t]$, $y[t]$, and $z[t]$. The 3 differential equations are here:
...
2
votes
4answers
199 views
1
vote
0answers
52 views
Evaluate the NDSolveValue at the condition point with replacement [closed]
I try to Evaluate something with replacement
...
1
vote
1answer
76 views
How to replace the expression in nest?
I need to calculate the following function with replacement in recurrence
...
1
vote
2answers
88 views
Confused by result of NDSolve for Second-Order nonlinear ODE
It is impossible to solve numerically a nonlinear second-order equation, although the initial conditions are given.
...
2
votes
1answer
146 views
(Numerical) calculation of nested integrals
The problem
I'd like to (numerically) compute nested integrals of the type $$I(a;k) \equiv \left( \prod_{i=1}^k \int_0^\infty \mathrm{d}x_i \right) \exp \left( - \frac{1}{4a} \sum_{i=1}^k \left( x_i - ...
1
vote
1answer
37 views
Getting message Set::setps: Kpr[x,y] in the part assignment is not a symbol
I use a loop to create a set of matrixes Subscript[k[x, y], i], depending on variables x, y. Then I create a large matrix
...
3
votes
0answers
42 views
Behavior of $MinPrecision seems to have changed between 12.0.0 and 12.1.1
I am running into a very weird bug where setting $MinPrecision to some value (in this case 200) has a very different and ...
0
votes
0answers
18 views
All formatting lost from a working notebook
I had a working notebook with title and normal cells. I opened and
all cells were merged to a normal (InputformDisplay type) cell, all titles and text cells are lost, that is, they became the same ...
1
vote
0answers
43 views
Need help with NestList [closed]
NestList::intnm: Non-negative machine-sized integer expected at position 3 in NestList[#1 + t&, 0, 8.].
What does the above error mean and how can I refer to result of ...
1
vote
1answer
82 views
Why DSolve cannot Find a General Solution for this ODE?
The Problem Given a mass m=1 moves in potential V(x)=|x|^3;
and x(0)=1,x'(0)=0;
So I set up
...
0
votes
1answer
86 views
Having problem in evaluating the eigenvalues of an $11\times11$ symmetric matrix in Mathematica [closed]
I am solving an $11\times11$ matrix in Mathematica. I am facing problem when I try to find the determinant or eigenvalues of this matrix. The error (Det::matsq/<...
0
votes
0answers
45 views
SystemException[“MemoryAllocationFailure”] in Integrate
Integrating products and ratios of piecewise linear functions throws the error ...
2
votes
1answer
48 views
DSolve implicit function of time
Apologies for the basic question.
I am trying to solve this differential equation for $w(t)$ as a function of $q(t)$: $$ \frac{dw(t)}{dt} = \mu_v \frac{R_{on}}{\delta} \frac{dq(t)}{dt}. $$
Solving ...
1
vote
1answer
32 views
Error message when referring to the value of a part of one element in a list [closed]
The following works fine to define an element of a two-argument list:
T[1, 2] = {3, 4, "yes"}
But when I try to change the third part, like this
...
1
vote
1answer
34 views
Manipulate giving errors when I plot the product of a step function and a continuous function
Riemann's prime counting function J (link) takes half-values at every jump-discontinuity. So, I define it thus:
...
1
vote
0answers
63 views
2
votes
0answers
50 views
Problem with stopping NDSolve after a condition is met
I'm trying to write a piece of Mathematica code that is essentially a differential equation solver that needs to take a specified function $V[t,q]$, and then numerically solves the differential ...
1
vote
2answers
142 views
Error message: “-1.99992 cannot be used as a variable” [closed]
could anyone please tell me how to fix this: I want to plot the solutions of a coupled ODE:
$\frac{1}{3} u\partial_x ^3 u = \frac{1}{2} \partial_x v; \ \partial_x\left( u \partial_x v - \frac{1}{2} u^...
0
votes
1answer
60 views
Integral involving orthogonal functions (quantum harmonic oscillator eigenstates)
I have a question about the capabilities of the Integrate command for general parameters.
We know that there is a system of functions:
...
0
votes
0answers
49 views
Serious Startup Error: Error code 603. What to do?
So my laptop shut down due to lack of battery with some open Mathematica notebooks that were saved but now Mathematica wont launch at all and I cannot find anywhere information about this error code. ...
0
votes
1answer
60 views
Why is this integral throwing a “MemoryAllocationFailure” error?
The following call to NIntegrate throws the error:
Throw::sysexc: Uncaught SystemException returned to top level. Can be caught with Catch[[Ellipsis], ...
0
votes
2answers
71 views
How to know, which constraint is being violated in linear programming problem?
my task is to minimize costs of dispatching various power plants in order to meet demand in a transmission grid. I solve the task as a linear programming problem with the help of Minimize[] function ...
0
votes
0answers
45 views
How to fix a ParametricNDSolveValue? - Encountered non-numerical value for a derivative at t == 0
How to fix a ParametricNDSolveValue? - "ParametricNDSolveValue::ndnum: Encountered non-numerical value for a derivative at t == 0."
I have tried ...
0
votes
0answers
24 views
FindRoot does not satisfy PrecisionGoal but gives no error message
I use FindRoot to find a root to the equation
...
0
votes
2answers
62 views
2
votes
5answers
127 views
Can't be solved using methods available
I'm stuck on this and chagrined I'm even asking, but this:
...
4
votes
2answers
148 views
Finding the number of even numbers in Pascal's triangle (code gives memory error)
I have the following code:
...
0
votes
0answers
51 views
InitializeBoundaryConditions::fembdnl: The dependent variable in the boundary condition needs to be linear [duplicate]
Checking the documentation on the error were of not that much help to me. Can someone please suggest how to deal with it?
...
