2,661 questions
-2
votes
0
answers
119
views
Boost or C++ standard library for special mathematical functions [closed]
I want to use spherical Bessel function and associated Legendre functions. There are two options:
Boost library
C++ standard library
https://en.cppreference.com/w/cpp/numeric/special_functions/...
4
votes
1
answer
118
views
In Haskell, why toRational (1/0) == infinity is False?
I couldn't find documentation for this behaviour and it looks like a bug ([Edit] it is indeed : gitlab.haskell.org/ghc/ghc/-/issues/10387). Am I missing something ?
In GHCi :
> import GHC.Real
...
- 764
-3
votes
1
answer
62
views
sort json object numerically by key
I have the following json format. It's basically a representation of the calendar:
{"month1": {"day1":{...}, "day2": {...}}, "month2": {...}}
I'd like to sort ...
- 19.2k
0
votes
0
answers
50
views
Apache Calcite with PostgreSQL: “DECIMAL precision 0 must be between 1 and 19” Exception
I am using Apache Calcite 1.38.0 along with the PostgreSQL JDBC driver version 42.7.2. When executing an SQL query through a JdbcSchema connection to my PostgreSQL database, I encountered an exception....
- 1
0
votes
0
answers
17
views
The number of derivatives returned by func() (x) must equal the length of the initial conditions vector (y)
I'm trying to define a parameter in my mathematical model "z", where my model is a system of ordinary differential equations, which is then solved using the function "ode" of the ...
0
votes
0
answers
35
views
Jacobi method converges faster than Gauss-Seidel in case of Laplace equation
It is need to solve the problem using the Jacobi method: d^T/dx^2 + d^2T/dy^2 = 0 with conditions at the boundaries of the square:
T(0, y) = 1, T(x, 1) = 1, dT/dx(1, y) = 1 - y, dT/dy(x, 0) = x.
...
0
votes
1
answer
136
views
How to find the index of the minimum cumulative sum in the face of floating-point rounding errors?
Call arr an array of float64 between −1 and 1. I want to find the index of the minimum of the cumulative sums of arr. My problem is that I cannot do this easily as the numbers in arr are of very ...
- 21.4k
0
votes
0
answers
26
views
Adding a NumericUpDown to a menu?
Windows Forms has a control NumericUpDown that allows the user to choose a number by clicking tiny up and down arrows, or entering a number via keys.
Is there a way to add this functionality, but ...
0
votes
1
answer
73
views
Problem in converting the datatype of a column in PostgreSQL
I created a whole text table to avoid problems in the import of the csv. After that I changed the data cleanup to "," in "." as number dividers to avoid problems with the delimiter....
0
votes
0
answers
29
views
Partial derivative of logistic function for Levenberg-Marquardt
I am trying to write code that will fit logistic function to set of data. I am using Levenberg-Marquardt routine (as given in Numerical Recipes 3rd edition) and that requires me to supply a function ...
- 2,658
4
votes
1
answer
103
views
How to compute sign(a² - b * c) * sqrt(abs(a² - b * c)) accurately with floating point arithmetics?
Question
I was wondering if there is a numerically accurate way to compute
sign(a² - b * c) * sqrt(abs(a² - b * c))
with floating point arithmetics because it suffers from (ordered from most to least ...
- 111
0
votes
1
answer
73
views
polynomial evaluation producing non-differentiable behavior in Python
I'm trying to evaluate a polynomial of degree 61. However, around the point sqrt(2) I get some weird behavior. The graph of the polynomial becomes erratic. What could be the reason for this. The ...
- 113
0
votes
1
answer
37
views
How to prevent non-numeric characters being put inside an input box
I am new to TypeScript and currently I am designing a BMR calculator. I have created a handleNumericInput function that only allows numbers to be accepted inside an input box but the problem is when I ...
- 75
0
votes
2
answers
153
views
Why 5.0 / 2 returns 2.5000000000000000 (scale of 16) instead of 2.5 (scale of 1)?
Fiddle
select 5.0 / 2
, pg_typeof(5.0 / 2);
pg_typeof
2.5000000000000000
numeric
Why the result is 2.5000000000000000?
When we insert 2.5 into a numeric column or select 2.5 from a numeric column ...
- 31
0
votes
3
answers
73
views
How can I extract the numeric portion before the first letter in a FileMaker calculation?
I have a field called Serial Number in FileMaker, and I need to extract the numeric portion of the string that appears before the first letter (A-Z), after removing the first 6 characters.
Here's the ...
- 3