# Questions tagged [numerical-value]

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

159 questions
Filter by
Sorted by
Tagged with
1answer
118 views

### How to test if a solution of NDSolve is positive

I want to solve a differential equation numerically and determine one of the parameters in the D.E. The goal is to determine $M$ such that the function goes asymptotically to zero or to put it in a ...
2answers
108 views

### Computing a sum with high precision

I am aware that a similar question has been asked, for example, here and here, but none of the proposed solutions solves my problem, so please wait before you mark this question as a duplicate. ...
1answer
75 views

### How do I to remove a factor of 1 [duplicate]

I evaluated Subscript[ε, 1, 2] = 0.5 Subscript[γ, 1, 2] 2 μ Subscript[ε, 1, 2] 1. μ Subscript[γ, 1, 2] How do I to remove ...
1answer
66 views

### How to make Mathematica show small and large results? [closed]

I have two equations with x=r+Log[-1+r] and v=(1-1/r)/r^3 forms. When I substitute ...
0answers
38 views

### Getting the coordinates of a specific point out of a plot [closed]

I have the following piece of code that in the first part calculates and plots a function and it uses it in the second part to perform an NDSolve. After that I am plotting two functions. What I would ...
1answer
129 views

### How to avoid rounding error, when exporting numerical values

How to avoid the rounding error, when exporting data like this: ra = Range[0.004, 0.074, 0.0005]; Export["range.txt", ra] The result is this:
0answers
96 views

### How solve this equation and plot the results?

I want to solve the following function and get values for $\omega$. $$\omega - \omega_{21} + i/\tau_{2} - s_{1}\alpha_{1}(\omega)[1+f(\omega)] = 0$$ The function $f(\omega)$ is the troublesome ...
1answer
44 views

1answer
101 views

I have this: ...
3answers
995 views

### Solve Laplace equation in Cylindrical - Polar Coordinates

Hey mathematica stackexchange!! I've got a (possibly stupid) problem. I've tried many things to no avail, and I've read every post I've found on Laplace's equation. Background: I'm trying to find the ...
1answer
143 views

### How to make Mathematica substitute exact numerical values of (derivatives) 2F1

I have a long output that contains Taylor expansion of some function. Some of the coefficients are combinations of the (derivatives of) 2F1 at nice integer values of the coefficients. I can see that ...
1answer
82 views

### Numerical error in compile, Strange behaviour in numerical evaluation

First of all, apologies for the large numbers, I couldn't find a working example for a far lower order and the zeros are necessary... my problem is this: I have a large polynomial (from high-order ...
1answer
56 views

### Partial Derivatives of numbers not evaluating?

I have code of the form someFunction[xx_?VectorQ] := 1 + anotherFunction[xx] myfunction[xx_?VectorQ]:= Sum[D[someFunction,xx[[a]]],{a,1,4}] After this evaluates, ...
0answers
54 views

### How to convert a dollar fraction into a normal dollar amount

I'm trying to use Mathematica to compute compounded interest. I used Wolfram Alpha, and it gave me the code ...
1answer
72 views

### Function not evaluating to zero - numerical errors

I have a complex but analytical expression that should always evaluate to zero for certain values, but I'm getting strange numerical noise I think I can avoid. The problem seems to occur in a ...
1answer
33 views

### Setting the parameters in a defined function vs replacement rule in the formula

I have the following definition in my Mathematica notebook. ...
1answer
39 views

### Question related to IntegerPart

I am having trouble understanding the following result: Through[{IntegerPart,FractionalPart}[{100 4.02}]] {{401}, {1.}} ...
0answers
59 views

### Integrate a multivariate function similar to a delta function

I am doing a code in Mathematica. I have the following function: ...
0answers
81 views

### Change of variables in integral is not working

Consider the matrix ...
1answer
88 views

1answer
92 views

### N[Product] and NProduct give different results

I have some trouble. I've been using finite product to study a certain function (see below). However, when I wanted to compute it precisely, I decided to use ...
1answer
84 views

### How to fix step size in do loop? [duplicate]

I apply the following command: Do[Print[var[u] = u], {u, -1, 1, 0.1}] It produces out put. But when i recall the value var[-0.4] as below: ...
3answers
293 views

### How to complete function which is not defined for all interval

I have a function testF22 like this ...