Questions tagged [warning-messages]

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1answer
139 views

Getting errors from NDSolve; what solver should I use instead? [closed]

How can I remove the error in the code below? I don't know the reason for getting this error. ...
2
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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 ...
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1answer
47 views

Error on DSolve

I've been trying to solve this initial value problem using 'DSolve[]': $$ \frac{dy}{dt}=1+t\space \sin(t\space y),\quad y(0)=0, \quad t=[0,2] $$ ...
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1answer
73 views
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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 ...
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2answers
1k views

Indeterminate expression 0^0 encountered

I'm new to Wolfram Mathematica so the the question may seem quite simple. I define the following function: ...
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2answers
231 views

Error Message NIntegrate: “The integrand … has evaluated to non-numerical values…”

When running the following code, I get the error message that "NIntegrate::inumr: The integrand ... has evaluated to non-numerical values for all sampling points in the region with boundaries {{0,0....
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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
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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
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0answers
88 views

Trying to solve a PDE — getting warnings I don't understand

Consider the partial differential equation ...
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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 ...
2
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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 - ...
7
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1answer
371 views

Understanding NDSolve::ndsz

I'm working on a largeish system of differential equations where I encounter the NDSolve::ndsz step size is effectively zero; singularity or stiff system suspected ...
3
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1answer
77 views

How to terminate a Do Loop when encounter FindRoot::lstol warning

While finding the roots of a system of non-linear equations, I am encountering the warning "FindRoot::lstol: The line search decreased the step size to within tolerance specified by AccuracyGoal and ...
0
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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....
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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{\...
2
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1answer
59 views

When does NDSolve issue zero step size error NDSolve::ndsz?

I want to detect directly when step size becomes "effectively" zero. The below example from the documentation throws the error message as expected: ...
0
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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
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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
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1answer
110 views

'Block' with 'Compile' gives an error

Here is a minimal example to the problem I face when using Compile with Block: ...
3
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1answer
62 views

Is there a way to customize how many of the same warning messages are printed?

I have an evaluation inside a Paralleltable which sometimes gives me warning messages. After a certain amount of warning messages it will say: ...
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1answer
81 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 ...
2
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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
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2answers
688 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 ...
0
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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
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1answer
52 views

Invalid comparison in Manipulation with Stepwise function

I want to draw a graph of the function that I specified using Piecewise. Though I can draw a graph, I keep getting errors saying invalid comparison with -xx + yy i attempted. The followings are my ...
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4answers
199 views
1
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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}] ...
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1answer
90 views
4
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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{...
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
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2answers
102 views

What makes a system be differential-algebraic equations?

I am trying to solve the equations in the following way: ...
0
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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
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: ...
0
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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: ...
1
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2answers
2k views

BarChart with error bars

I need to plot BarChart with the error bars. What's the most straightforward way to do it?#plot range from 8 to 10 ...
1
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0answers
52 views

Evaluate the NDSolveValue at the condition point with replacement [closed]

I try to Evaluate something with replacement ...
1
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1answer
76 views

How to replace the expression in nest?

I need to calculate the following function with replacement in recurrence ...
1
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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. ...
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: ...
1
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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
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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
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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
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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 ...
0
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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 ...
2
votes
1answer
55 views

How to turn on all suppressed error messages

I have a variety of possible errors in each iteration of a for loop. If, in one iteration of the loop, there are more than 3 error messages of the same kind, I am happy that the rest are suppressed. ...
3
votes
2answers
340 views

Nonlinear system of ODEs with boundary conditions

I'm trying solve this problem: g'(r) = a(r)g(r)/r, (1/r)a'(r) = g(r)^2-1 which have the following boundary conditions: a(0)=n ...
0
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0answers
45 views

SystemException[“MemoryAllocationFailure”] in Integrate

Integrating products and ratios of piecewise linear functions throws the error ...
1
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1answer
63 views

Correcting error messages emitted by ListPlot

I have an assignment to use Module and in which I have to implement: The input of the program are a list of numbers and a list of strings Check whether every ...

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