Questions tagged [parameters]

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Find the parameter in NDSolve giving the desired solution

I find myselef in choosing by hand the right parameter that let ParametricNDSolve return the desidered solution. I'm sure there is an easy alternative, but I can't ...
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1 vote
1 answer
58 views

NonlinearFit with series coefficients

I have a set of data: ...
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-1 votes
2 answers
79 views

Plotting the parameter space corresponding to a solvable equation

I am considering a function $f(T, c_1, c_2)$ for which I would like to plot the region in the $c_1$ and $c_2$ parameter space that corresponds to the values of $c_1$ and $c_2$ such that $f(T)=0$ has a ...
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1 answer
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How to organise definitions that contain named parameters

I have lots of definitions of (usually numeric) quantities that depend on parameters; they're mostly matrices (in the actual code, there are many more definitions): ...
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1 answer
67 views

How do I calculate Mean Squared Error of parameters alpha and beta? [closed]

...
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3 votes
2 answers
269 views

Problem with solving a linear ODE with a parameter

I have been struggling with the following ode for several weeks, but I fail to solve it. So I post this question and my attempts and expect someone here could give some suggestions. First, define an ...
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1 answer
53 views

Integrate and InverseFunction

I solve an easy example to check that Mathematica can understand the difference between ArcTan and ArcTanh but as you see here I can't get Arctanh??!! Even I don't know why the inverse function is not ...
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1 vote
0 answers
45 views

How to fix a parameter in SolveAlways

In expression: SolveAlways[f1(a)+f2(b)x+f3(c)x^2+f4(d)x^3==f5(d)x^2+f6(e),x] Functions fi are known. How do I tell mathematica that d is a fixed constant?. I want ...
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0 answers
26 views

Comparing parameter regimes workflow

I have some code that relies on some parameters. I pick a set of parameters, calculate some things, solve some differential equations then plot various things with the solution. Ideally I'd like to ...
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  • 345
1 vote
3 answers
184 views

How to specify the domain of a parameter?

There is a similar post: How to specify the domain of a variable?, but it doesn't work well for me. I want to evaluate the integral below, with a parameter $\gamma$. The result is obviously different ...
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2 votes
1 answer
81 views

Table of surface Parametric draw

I'm trying to reproduce this kind of graph for a spherical cap, with different span ratios. I tried with this: ...
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0 votes
0 answers
112 views

Solve Differential Equation with Boundary Conditions (lengthy equation)

I have a lengthy equation to be substitute into a differential equation. I used DSolve to generate the output. However, it took me more than 3 hours and it still running. The DE is the convective-...
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1 vote
3 answers
53 views

Problem with ParameterFitting:""The function value...is not a list of real numbers..."

I'm trying to use the data: ...
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0 votes
1 answer
65 views

Restrict the domain of a function (and plot) it) when it depends on the value of a parameter

I know similar questions have been asked, but I am very new at Mathematica and other questions/answers are quite complex and do not suit the code I want to write. I want to restrict the domain of the ...
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  • 107
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1 answer
72 views

Solve in parametric equations in term of a set of parameters

I am not sure the title is right but let me explain. I have the relations ...
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  • 151
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0 answers
28 views

Logarithmic NonlinearFit with 10 parameters? Is Not a Real Number

I am trying to fit a collection of data with a fairly complicated function, and have been running into some errors. I am very new mathematica user, and am not really sure where I am going. This is my ...
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  • 1
0 votes
2 answers
50 views

How to make the third parameter optional and adding some condition?

I have a function as follows. The function has 3 parameters. Now I would like to make the third parameter i optional. So you call call it like ...
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1 vote
1 answer
55 views

How to initiate a matrix with indexed parameters [closed]

I couldn't find it in the documentation, so I'm posting it here. I want to create two by two matrices as follows: $$ `W = \begin{bmatrix}w_{11} & w_{12} \\ w_{21} & w_{22} \end{bmatrix}, V = \...
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1 vote
3 answers
70 views

How to ask Mathematica to do the given operation for a set of parameters?

I have a set of numbers like this s = {a, b, c, d, e, f, ..., g, h} and I would like to ask Mathematica to do the following operation (to sum the subtractions of ...
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-3 votes
1 answer
52 views

Find parameter distribution how i know any initial value i must put?

FindMaximum::eit: The algorithm does not converge to the tolerance of _4.806217383937354`*^-6_ in _500_ iterations
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1 vote
1 answer
45 views

How to pass a URL parameter to FormPage?

I'm trying to pass a parameter on a FormPage. I know that passing parameters on a APIFunction works, like: https://wolframcloud.com/...?x=5&y=10 But, I see no ...
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  • 138
0 votes
1 answer
32 views

Solving equation for specified parameters

I have a long expression which depends of several parameters ...
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-2 votes
1 answer
71 views

When i use findparameterdistribution parameters are diffient from in reasearch why? [duplicate]

This is Chen weibull distribution ...
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  • 29
0 votes
1 answer
84 views

Why does FindDistributionParameters[] fail to converge for this distribution? [closed]

During testing my code for calculate parameters The following exception is thrown: ...
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  • 29
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1 answer
97 views

Trying to find values of two parameters that match the boundary conditions defined

I have been trying to solve for the values of two parameters that satisfy the boundary conditions set for a set of equations set. The below is the code. ...
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  • 3
2 votes
2 answers
68 views

How to replace one parameter with multiple values

I am a beginner. I have a function with one parameter and I would like to replace a list of values that have names. I would like a result so that the names are not lost. ...
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  • 21
5 votes
1 answer
175 views

Automatic backup on Mathematica

When there’s a power outage and I’ve done a lot of work on Mathematica, I lose all the informations. Is there a setup on Mathematica to make an automatic backup. Knowing that on "wolfram cloud&...
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3 votes
1 answer
69 views

Defining $f(x)=mx+b$ with $m,b$ separate versus `f[m_ ,b_ ,x_]:=mx+b`

Suppose I want to define a function $f(x)=mx+b$. And suppose I might want to change $m$ or $b$ later. Specifically, suppose I initially want $m=-2,b=10$, but maybe will change these values later Two ...
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1 vote
2 answers
149 views

Extracting the component distribution parameters from a mixed-normal distribution (for n > 2 normal)

I'm trying to extract the distribution parameters of the sub-distributions which comprise a mixed normal distribution. I'll give my attempts so far. First the simulated data: ...
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  • 2,291
3 votes
2 answers
269 views

How to find explicit hyperplane in SupportVectorMachine

I am using the SupportVectorMachine classfier: e.g., (* let me use Linear kernel for simplicity *) ...
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0 votes
1 answer
197 views

NDSolve: input a value for a parameter from a list of values

I have a parameter in an equation which has a different value at each step from a list of values calculated in a former NDSolve differential equation. While what I am trying to achieve is more ...
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  • 1
0 votes
0 answers
65 views

NDSolve and NIntegrate with parameters

I have a problem with a numeric computation. I should solve a numeric ODE and the rhs is a numeric parametric function that I find with several NIntegrate. I'd like ...
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  • 1
1 vote
1 answer
81 views

Find the condition under which an inequality holds

I've got an inequality of 8 non-negative parameters (arising from a 5x5 matrix) and would like to find a condition under which my inequality holds. The condition would be an inequality too of these ...
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6 votes
3 answers
202 views

Verify an inequality of many parameters

I've got an inequality of 10 non-negative parameters (arising from a 5x5 matrix) and would like to verify whether it holds. I tried the following, which doesn't seem to work: ...
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  • 85
4 votes
1 answer
126 views

Can you force Integrate[] to find a complete symbolic solution for all variables?

(As I've asked on the Math StackExchange and on a related previous question), I am interested in getting a complete symbolic solution to the integral of an expression with a lot of unassigned ...
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1 vote
2 answers
281 views

Unreliable parameters errors from NonlinearModelFit [closed]

Goodmorning everyone, I'm trying to fit the following data ...
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  • 13
1 vote
0 answers
111 views

Minimize chi square fot non-linear fit

I recently started using Mathematica, so I have a question. I would like to find the parameters of a non-linear function by minimizing the chi square. How could I do? The function would be like this : ...
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0 votes
0 answers
70 views

Why do I keep getting these error messages?

I am trying to fit a parametric differential equation system to the data of the infection cases in Hungary. I keep getting the error messages: ParametricNDSolveValue::ndcf: Repeated convergence ...
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  • 29
0 votes
2 answers
100 views

Steady State case for differential equations

I need to write these equations in steady state form (time derivatives set to 0), and then substitute in values for the parameters (e,d,q,f). However, I don't understand how to do this as if I set the ...
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  • 199
1 vote
0 answers
136 views

Parameter space for a theory [closed]

I was trying to learn to make plots of parameter spaces. For example, if I have a theory with one free parameter $$g(z)=\alpha(1+z)^2$$ I know that you can plot the function ass function of $z$, ...
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  • 585
0 votes
0 answers
51 views

How to plot functions of multiple variables with multiple constraints as a function of just one variable

Essentially I would like to plot the solutions to the following equations in terms of only 2 of the variables included: I have the following simultaneous equations: ...
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1 vote
0 answers
51 views

String arguments break optional argument default values? [duplicate]

Following a tip in this post, I use string parameters to label my functions. For example, instead of f[x]:=x^2, I use ...
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  • 699
2 votes
1 answer
72 views

Problem with solving a system of differential equations within Manipulate

I'm triing to do this commands: ...
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1 vote
2 answers
249 views

Pick out elements from a list of lists using criteria

Consider a list of lists in this form (with a shape $ m \times n \times 3 $): ...
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  • 661
6 votes
1 answer
187 views

Mathematica slow at estimating vector autoregressive model parameters

I have been trying to obtain VAR model parameters using EstimatedProcess and FindProcessParameters. It seems to take a very long time as soon as I have more than 6 or 7 time series and lag length >2. ...
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6 votes
1 answer
417 views

Solve an ODE with parameters in a boundary condition

Consider the ODE: ode = y''''[x] - 2*k^2*y''[x] + k^4*y[x] == I*k*a*((2*x - x^2 - c)*(y''[x] - k^2*y[x]) + 2*y[x]); in which a...
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1 vote
0 answers
106 views

NDSolve issue, potential singularity or stiff system

I have the following parameters, equations, and NDSolve solution set up as such: ...
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6 votes
1 answer
259 views

Nonlinear differential equation with unknown parameter and integral form boundary condition

I'm trying to solve numerically a non-linear problem in order to determine the velocity field ($U$) and the film thickness ($h$) of a non-Newtonian fluid over an inclined plane. The equations are, $$\...
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1 vote
0 answers
86 views

Big Confidence Interval for seemingly rather accurate variable, NonLinearModelFit [closed]

I used NonLinearModelFit to fit a function of the form a*Abs(Cos(x))^b to a set of 5 points, that each have a uncertainty. My ...
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1 vote
0 answers
40 views

What is wrong with this input? [closed]

I've followed the examples from the introduction to mathematica for math students: https://www.wolfram.com/language/fast-introduction-for-math-students/en/more-plots-in-2d/ ...
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