# Questions tagged [numerical-value]

Question relating numerical representations, operations and methods, including approximate results instead of exact symbolic results.

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### Explain difference in Floor[Log[10., 1000]] and Floor[Log[10, 1000]] [closed]

I executed the following function: Floor[Log[10., 1000]] I expected as result: 3 but the result was ...
59 views

### Problem with Solve and PrimeZetaP

I assume this is something to do with limits on numerical precision, but can someone explain the difference in output between these two Solve problems: ...
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### Using Around with NDSolve

I was trying to obtain the same result of a differential equation with to different methods the first one is based on DSolve and the second one is based on NDSolve ...
53 views

### MemberQ giving false when the answer is true? [duplicate]

Lets generate a large grid grid=Table[{i,j},{i,0,10,.01},{j,0,10,.01}] MemberQ[grid,{7.02,.02}] The above MemberQ gives me False. (even though it must be true ...
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### Using NDSolve for differential equations

I'm trying to numerically solve the following differential equations eqs for plotting the bifurcation diagram. However, under special values of the parameter u, I get a problem when calculating the ...
72 views

### Proving the positive semidefiniteness of a 6X6 symbolic matrix

Specifically, I want to check the positive semidefiniteness of the following 6X6 symbolic matrix ...
141 views

### Evaluate and Plot x=x+1

I have a function of the form x=x+dx, whereas x(z) and dx(x,z) both depend on a increasing integer. Now I would like to evaluate this function after n time steps. In addition to that I'd like to plot ...
68 views

### Is this false solution? [closed]

I tried W.A to find the solution for $log(-i)$ and the result is $log(-i) = -i\pi/2$ . But I calculate 'by hand' that $e^{-i\pi/2} = i ?$ . Is this result / solution false ?
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### Derivative does not correspond to function

I have an implicitly defined function, f[p], and I plot it together with its derivative. As is clear from the picture, the function is increasing, but the ...
82 views

### Laplace equation DirichletCondition ignored

My goal is to find out force between two parallel identical disks with Voltage difference. To solve this, I tried to use laplace equation. And below is my code. where R is radius of disks, d is ...
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### Checking NDEigensystem Results

I'm looking to verify the output of a call to NDEigensystem. I'm doing this by plotting the operator acting on the Interpolating Function outputs versus the ...
241 views

### Simplify appears to give different results

I have an issue with Simplify (and FullSimplify) giving a different numerical expression to the pre-Simplified expression. The function is an alternating sum of trigonometric quantities: ...
37 views

### What is used for the % symbol in mathematica? [duplicate]

Im new in mathematica i want to know logic about this program. I got this code: {{vo, vn, Ii}} = {vo, vn, Ii} /. %; i know that the syntax /. is for replacement but i dont know whats going on with ...
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### Equation solving for approximate solutions when function has numerical integration in it

I have an equation that is of one variable lat and has a numerical integration in it t from 0 to 1. Let's say it's given by <...
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I have this ...
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### Having problems with using TableForm to format a table

I want to make a table of various values of the logistic curve given by l[x_] := 1/(1 + E^((-k)*(x - \[Alpha]))). In basic form, this is dead easy. However, I want ...
I'd like to fit a branch of the Lambert function : -ProductLog[-1, x] in the interval $[-0.35,0]$ with a function of the form $-a\log(-bx)+c+d x$ or $-a\log(-x)+... 1answer 174 views ### Mathematica and IBVP mixing temporal and spatial derivatives The following PDE's-system-solving code ... 1answer 68 views ### Increasing MaxExtraPrecision arbitrarily changes numerical result I am trying to confirm that a function$f$satisfies a particular differential equation of the type$D f=0$, for some differential operator$D$. I set$Df$as Diffeq... 1answer 88 views ### How to extract the minimal value from NMinimize? [closed] According to the manual, if I calculate NMinimize[x^4 - 3 x^2 - x, x] that returns {-3.51391, {x -> 1.30084}}, I can extract the minimal value -3.51391 using <... 2answers 59 views ### Numerics & List Manipulation:ListCorrelate: yield$\{-f1 + f2, \dots, -f2 + f4, \dots\}$from$\{f1, f2, f3, f4, f5\}$The command ListCorrelate[{-1, 1}, {f1, f2, f3, f4, f5}] yields {-f1 + f2, -f2 + f3, -f3 + f4, -f4 + f5} is there any simple way to get {-f1 + f2, -f1 + ... 2answers 206 views ### Help for Solving Two Equations For Two Unknows (from a Paper) I am trying to reproduce numerically the results found in this paper: https://ieeexplore.ieee.org/document/1707778 You don't necessarily need to read it. Basically I boils down to solving a two ... 4answers 168 views ### How to solve equation in integer numbers I would like to solve an equation like this$\frac{\log(2)}{\log(3)}=\frac{n-0.5}{k-0.5}$where$n$,$k$are positive integers and$\log$is natural logarithm. Of course, I can do only numerical ... 2answers 112 views ### Sampling data from numerical values of density distribution of nucleons How could i sample my data which follows distribution if i have only numerical values of density distribution as an example data attached as in picture I tried but do not know how to do it. The data:... 3answers 33 views ### Low precision from function returning matrix Got a function depending on single parameter "t" defined below which returns a 2 by 2 matrix ... 1answer 141 views ### Second-order nonlinear boundary value problem I am trying to follow this work, in which Eq. (11), the 2nd-order, nonlinear differential equation depends on a pair of parameters$ (\kappa, h) $. But now I only care about the case with a vanishing$...
I have a function defined on $S^6 \times S^6$ (two spheres embedded in $\mathbb{R}^7$ individually). Let us call this vector $\vec{f}(\vec{x},\vec{y})$, where $\vec{x}$ and $\vec{y}$ are ...