890 questions
0
votes
1
answer
62
views
Exponential Decay Screen Element Animation
Pseudocode:
DistanceToMove = distanceToMove*decayFactor;
xPos = xPos + distanceToMove;
I am attempting to have a screen element begin at a specific place and go to a final position at a decreasing ...
2
votes
1
answer
133
views
How to fit different Exponential models for decay and growth and get the parameters?
I am trying to fit exponential to my data in r to get regression parameters. I would appreciate if you could please help me with. I have tried nls() and didn't work, tried different datasets as well. ...
- 321
2
votes
1
answer
111
views
How can I set an OFFSET = 100 in nls (Nonlinear Least Squares) coupled with the SSbiexp or SSasympOFF (self-starting) functions in R?
I am using self-starting functions to estimate the best constants for my models in R software. But it does not allow me to constrain my offset (y=100, x=0) to be 100.
The two component exponential ...
- 21
1
vote
1
answer
58
views
Exponential function for search algorithm
I implemented a linear function for a search algorithm, that boosts a document according to its time since upload. So the newer a document the more likely it will be presented for a given search term. ...
- 316
1
vote
1
answer
84
views
Error in lm.fit(x,y,offset = offset, singular.ok,...) for exponential lm() model in R
I am trying to apply a exponential regression on the given data frame :
df <- structure(list(Type_stat = c("Vitesse_min", "Vitesse_max", "Vitesse_min",
"...
- 410
1
vote
2
answers
113
views
Sampling from a Superexponential Population in Polynomial Time
I'd like to sample from a well-defined population of super-exponential size with uniform probability among the population. For example, say the population is the set of unique permutations of ...
1
vote
1
answer
104
views
How do I fit an exponential 3D surface to measured data
This is my data:
[[1.0183786345931547, 1.0299586760768078, 1.038641346963767, 1.0450398412805133, 1.194598528164483], [1.0498980141678536, 1.0740481275807727, 1.101990429736493, 1.1528998376687427, 1....
3
votes
2
answers
145
views
Why raising a vector of negative values to a fractional power gives NaN [duplicate]
If I generate a vector of values, some of which are negative:
d <- rnorm(1000, 4, 10)
z <- sapply(d, function(x) x^1.2)
z will contain a mix of real values and NaNs. Any values that were ...
- 8,270
-1
votes
2
answers
601
views
Double exponential fit in Python
I have problem related to curve_fit in Python. Specifically, I am trying to model double exponential data.
I am trying to model data. The fits are good by the eye, but when I look at the parameters ...
-4
votes
1
answer
512
views
Java double converts more than 4 decimal points to exponential format and stores the same exponential format in the DB
I have an entity class(Account) wherein I have the following property
@Column(name = "balance", precision = 10, scale = 10, nullable = false)
Double balance;
Then in one of my spring ...
- 57
0
votes
0
answers
63
views
Code for non-linear constraints in CPlex opl
`Can anyone help me to code this constraint in Cplex opl . It seems to be nonlinear constraint but I do not know how to convert to linear constraint correctly:"enter image description here
l_jt_y[...
-1
votes
1
answer
87
views
calculating r using nth root
I am trying to calculate r at a specific time, or f(t_max). I am using a scale from 0 to 255. So I am trying to calculate the correct rate value for exponential growth at t_max = 255, with an initial ...
- 1
3
votes
1
answer
125
views
Element by element exponential of a sparse matrix in R
I have a large sparse matrix (dgCMatrix) in R, and I would like to have the exponential of each element of this matrix. More precisely, I would like to do 1-exp(-x) to each element of the matrix. ...
0
votes
1
answer
624
views
curve fitting exponential function python
I need to apply curve fitting (look at the graph). However, I am struggling to find the initial parameters based on a visual (looking at the plot). So how do I now which value to pick for a, b or c. ...
0
votes
1
answer
424
views
What is the fastest way to do a matrix exponential
I need to calculate the matrix exponential (https://en.wikipedia.org/wiki/Matrix_exponential) for matrices of size upto 1000*1000.
As of now, in python, scipy.linalg.expm (https://docs.scipy.org/doc/...
0
votes
2
answers
216
views
Three variables exponential equations in Python - solver options
Asking here is my last resort, I do not know where else to look or what my next option would be, apart from changing languages.
I have a set of 3 heavy exponential equations, with 3 variables. All ...
- 11
2
votes
0
answers
822
views
Formatting numerical tick labels into exponential notation in ggplot2, without rescaling x- or y-axis
I am not very proficient in R, and I have stumbled upon an obstacle when using ggplot2. I have a plot with large numbers on both the x and y axis of the plot. Since I am dealing with large numbers, ...
- 21
1
vote
1
answer
60
views
error messages fitting a non-linear exponential model between two variables
I have two variables that I'm trying to model the relationship between and extract the residuals. The relationship between the two variables is clearly a non-linear exponential relationship. I've ...
- 1,527
0
votes
1
answer
105
views
How to fix this error message occurring all the time during my non linear regression nlsLM method
I'm still trying to get exponential curve lines on my data. I'm having abundance values in function of time and I want to apply and exponential regression on the first points. I've found a package ...
- 1
1
vote
1
answer
799
views
Explicit formula for EWMA(n) in Python
I have the following pandas.core.series.Series:
x=pd.Series([17.39, 8.70, 2.90, 1.45, 1.45]) for t=0,1,2,3,4.
When I try x.ewm(span=2).mean() I get the following results:
17.39, 10.87, 5.35, 2.71, 1....
- 362
-4
votes
2
answers
127
views
I am having a hard time converting fluid dynamics equation into MATLAB code
I converted these two equations into MATLAB code before but I lost the file and now I am trying to write them again but there is a problem and I can't figure it out.
This is the main equation:
This ...
0
votes
1
answer
38
views
'Accidental' Exponentials
(Solved, however I would love to know WHY this happens.)
So,I have this script which should make a huge block of "brick" parts. The idea was for something like breaking them in some way (...
- 26
1
vote
2
answers
858
views
Curve fitting in python compared to excel (variance in results)
I am fairly new to python, while I have used matlab quite a bit before. Currently I am trying to do an exponential curve fit to a semi logarithmic plot. Down below is the code I've currently got.
...
- 33
0
votes
1
answer
221
views
Decay functions and ggplot - How do I fit a decay function to my data, with conf intervals?
I am working with concentration over time data. The intent is to find a model for the decay rate of the phenol content of algae over time. Not much info is available on the literature about the shape ...
0
votes
0
answers
457
views
Exponential conversion to number is wrong in SQL Server
I am inserting some data from python to sql server. In the dataframe, the data looks ok. However after inserting into sql table, the number converts to some exponential expression. I tried to convert ...
- 453