# Tagged Questions

Questions on the numerical functions of Mathematica, implementing numerical methods and numerical computing with Mathematica.

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### How to fit parameters, not functions?

Given a set of parameters ...
281 views

### Trouble with shooting method for a 4th-order stiff ODE

The ODE I need to solve is $$\left(y^3y^{\prime\prime\prime}\right)^\prime+\frac{5}{8}xy^\prime-\frac{1}{2}y+\frac{c}{y}=0$$ where $\prime$ denotes differentiation, $c$ is a constant and $0<c\le1$....
45 views

### Differential equation for a list with parameter dependent function

I am having a differential equation: y' = (1 - y) - f[y, mu] y; f is a hysteretic function that depends on y and on the derivative of y: ...
400 views

### Bug: Wrong results from NSolve on coupled polynomials. WorkingPrecision->Automatic fails

OP UPDATE: I received an email from WR on 1-18-2016: "...It does appear that the NSolve function is not behaving properly in this case and I have forwarded an incident report to our developers with ...
205 views

### Maximized value of a function as an additional constraint on a variable

I want to maximize a function $f(b, h)$ with respect to its arguments and subject to some additional constraints. If these constraints are satisfied, $f$ is increasing in $h$. I then want to find an ...
396 views

### Wrong result of simple math calculation. Is it possibly a bug of the program? [closed]

I encounter the following issue accidentally (shown in the screenshot) which is very odd to me. The output[4] and [5] is obviously wrong. But with the input value of 991.91, it turns out to be right (...
141 views

### Chopping matrix elements, real or imaginary

An undesired shape of a matrix has the following form: which is created by ...
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420 views

### Solve function doesn't work

I have the following system of equations that I need to solve: ...
483 views

### Laplace PDE in a polar coordinate system

I want to solve a Laplace PDE in a polar coordinate system with finite difference method, but I have a problem with boundary conditions at r = 0. Here is what I ...
73 views

### Handling Accuracy and Simplifying

I have the following problem. I have a system of non-linear equations that I log-linearize around a certain point, let's call it point A, using a function that I ...
38 views

### How can I perform arithmetic on a list integers and some other exact numbers and get decimal numbers in the result?

I want to do a simple calculation with a list with Pi and 10^-6 and get a list of decimal numbers as the result. ...
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### Maximizing over an integral with a single parameter

There is probably a neat approach to solve this problem...but can't get to it at the moment. How do you maximize an integral with respect to a single parameter? My code below produces error messages. ...
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### Multi-Precision [duplicate]

I have read in some numerical Laplace inversion papers that we can take advantage of multi-precision environment in Mathematica , Maple and etc.Can someone please explain it for me why it is not ...
76 views

### Improving working precision of LegendreP[n,x]? [duplicate]

I was trying to evaluate N[LegendreP[5,0.1]] The cell gives me: N[LegendreP[5,0.1]]=0.178829 However I wanted more ...
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### CharacteristicPolynomial returns 0

I have a following matrix. ...
353 views

### Does NRoots own an abstract counterpart? If not, can we write one?

We know when solving linear algebra equations, despite its abstract syntax, LinearSolve is much faster compared to Solve: ...
343 views

### Infinite base two number to base ten

Suppose I have a base two number that repeats itself every five places (a number $x$ such that $0\le x<1$. For example: $$x=0.101011010110101101011010110101101011010110101...$$ What would be a ...
116 views

### Impact Crater Sim. with added criteria

I have been trying with out success to edit this impact crater simulation script into producing a variable which calculates crater density. In addition I have been trying to figure out how to ...
45 views