# Questions tagged [warning-messages]

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### 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 ...
704 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 ...
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### 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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### 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 ...
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### 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 ...
58 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 ...
100 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 ...
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### 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/<...
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### SystemException["MemoryAllocationFailure"] in Integrate

Integrating products and ratios of piecewise linear functions throws the error ...
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### 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 ...
36 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 ...
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### 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: ...
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### 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 ...
232 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^...
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### 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: ...
56 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. ...
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### 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], ...
101 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 ...
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### 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 ...
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### FindRoot does not satisfy PrecisionGoal but gives no error message

I use FindRoot to find a root to the equation ...
63 views

### Syntax error using Plot

Why is the error coming and what should I do to resolve it The code is ...
139 views

### Can't be solved using methods available

I'm stuck on this and chagrined I'm even asking, but this: ...
161 views

### Finding the number of even numbers in Pascal's triangle (code gives memory error)

I have the following code: ...
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### 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? ...
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### 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: ...
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### avoid using protected variable names in defining static pure functions

I will provide one example to show what the problem is. Collatz[m_] := Collatz[m] = 1 + If[EvenQ[m], Collatz[m/2], Collatz[3 m + 1]]; Collatz := 0; this ...
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### DSolve for System of Non-Homogeneous Differential Equation

Solve: x' = Ax + b Given: A = {{1, 2}, {3, 4}}; b = {{e^{t}},{2}}; This will solve if b == 0 DSolve[{x1'[t], x2'[t]} == a.{x1[t], x2[t]}, {x1[t], x2[t]}, t] But if ...
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### the number of equation does not match the number of variables

Excuse me , can you help me , please ? When i make run for this programme it give me a wrong that the number of equations does not match the number of variables ,,,, I try a lot on finding the wrong ...
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### Errors with assigment and no errors with replacement rule, why? [closed]

So I have an expression, let's call it f11 which is a function of t of this form f11= a1*t^(-4)+ a3*t^(-3)+... and so on up until a finite positive power of t. In ...
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### Getting error when I substitute PDE for ODE

The following code works perfectly: ...
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### NDSolve: how the initial step of finding explicit derivatives can be avoided?

There are several posts here devoted to resolving the following error message of NDSolve (NDSolve::ntdvdae, ...
52 views

I have some complicated function that depends on a few parameters that I need to integrate. It is integrated in the fastest way by using "AdaptiveMonteCarlo" method. However, I have found ...
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### BarChart does not display asymmetric error bars correctly

BarChart seems to read the uncertainty in elements the other way around. The object: Around[5, {1, 10}] is evaluated as . However, when you use it in a BarChart, the uncertainties are swapped: ...
110 views

### Maximize: x in Vectors[5, R] is not a valid variable

I am learning how to do optimization with a variable number of variables in Mathematica. I tried to write one experiment that I need to do but I have failed to get even a stripped-down version working....