# Tagged Questions

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

2k views

### Annoying display truncation of numerical results

I have a lot of data to inspect. An example of a number in my program is 123.189094 This gets displayed as 123.189 ...
89 views

### FindMinimum step size too small

I'm running a simulation of an electromagnetic system using Radia, an external code that is run from Mathematica. I want to use FindMinimum to determine some ...
398 views

### How to implement custom integration rules for use by NIntegrate?

How can NIntegrate be extended with custom implementation of integration rules? This answer of the question "Monte Carlo integration with random numbers generated ...
507 views

### NDSolve and memory usage

After some googling, i've found similar problems around, but didn't find a 100% satisfactory answer, so let me ask here: I'd like to solve a 1+1 problem using the method of lines. In spherical ...
160 views

### How to implement custom NIntegrate integration strategies?

How can new integration strategies algorithms be used with NIntegrate? This is a different type of extension than the extensions with new integration rules, as ...
45 views

### How can I do numerical calculation directly without any symbolic calculation? [duplicate]

Here I define a set of functions: ...
125 views

### Machine-Precision and Arbitrary Precision [closed]

What is meant by a machine number in the Mathematica documentation? What is the difference between machine-precision and fixed-point precision? What is arbitrary precision?
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### Why does a badly conditioned matrix give a totally different results in LinearSolve function? [closed]

Here I define a vector: C1p[n_, h_] := C1p[n, h] = LinearSolve[D1p[n, h], F1p[n, h]]; with 4*4 Matrix D1p[n,h] badly ...
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### Evaluation of Element?

What is the Mathematica reasoning behind the result of the first two elements on the second row of the following table? ...
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I bought the Home Edition of Mathematica online 0.5 G of memory and costs \$150 per year. When I calculated the median of outputs from$[0,1]$with an interval of$.000001$I ended up with the ... 2answers 132 views ### Multiplication non-deterministic? I have two vectors of 134 elements each ($mu$, and$gt$).$mu$contains Integers, and$gt$contains machine precision Reals. I execute the following simple expression multiple times without changing ... 0answers 53 views ### Numerically parameterize portion of$F[x,y]==0$I have a relatively complicated function of two variables F[x,y] whose zero locus contains a number of intersecting paths in the$x,y$-plane. A problem I've been ... 0answers 268 views ### Problem with NDSolve in Mathematica 9 / 10 I'm having trouble by solving the following differential equation in Mathematica 9 and 10, where the code works fine in version 7: ... 2answers 895 views ### Numerical solution of Bessel-like equation using NDSolve I need to calculate solution of Bessel-like equation having general form:$\frac{d^2F}{dr^2}+\frac{1}{r}\frac{dF}{dr}+Q(r)F(r)=0$. Problems come from the points near$r=0$leading to numeric errors. ... 0answers 30 views ### Copy-pasting a floating point number [duplicate] Here is a behavior of the Mathematica front end which confuses me. Type N[Sqrt[2]] The displayed output is 1.41421 ... 0answers 176 views ### Is manual adjustment of AccuracyGoal and PrecisionGoal useless? This is a problem confusing me for years. AccuracyGoal and PrecisionGoal are two options that I never truly understand and, to ... 1answer 101 views ### Understanding difference between NIntegrate result and home-cooked Simpson's rule In this question I am asking about the different results I get between NIntegrate-ing a function of two variables vs. "doing it myself" with my own implementation ... 0answers 57 views ### Numerical fitting trajectory to model that has NDSolve I have a model which describes the motion of an object on a plane. ... 2answers 156 views ### Accuracy and WorkingPrecision Observe that ... 1answer 115 views ### How to calculate this complex expression? I have a complex expression as follows, ... 4answers 295 views ### Does Mathematica have an equivalent of C's nextafter? In C (and many other programming languages), there is a function double nextafter(double x, double y) which takes two (IEEE 754) floating-point numbers and ... 2answers 80 views ### Determining the value at which a function becomes non-real or undefined If I have a function$f(x)$that I only know numerically and that returns a real value for some range of values$-\infty < x \leq a$and complex values for$a < x < \infty$, how can I ... 1answer 77 views ### Using loops to draw multiple polygons and discretizing them I am trying to plot the first eigenvalue of the Laplacian operator with zero Dirichlet condition on following figure against decreasing values of$\varepsilon$. I used ... 1answer 58 views ### MachinePrecision versus$MachinePrecision in NDSolve

I'd like to understand why one of these inputs gives me an error and the other doesn't: ...
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### SetPrecision on a decimal gives imprecise result [duplicate]

I noticed that SetPrecision doesn't actually guarantee that my number is as precise as I want: ...
31 views

### Use “FindFit” for Multi-variable Polynomial Fit

I'm interested in defining three input vectors: $L=\{L_{1}, \ldots, L_{N} \}$ $W=\{W_{1}, \ldots, W_{N} \}$ $Q=\{Q_{1}, \ldots, Q_{N} \}$ and I'm hoping to be able to input a number for each of ...
485 views

### How to create internally optimized expression for computing with high WorkingPrecision?

I have large dataset and need to fit rather complicated function on it with different values of one of its parameters (this parameter must be fixed in every fit). I use the ...
74 views

### Implementing the Cimmino method [closed]

What am I doing wrong? I am trying to implement the Cimmino method, an iterative method for the solution of linear algebraic systems. The final output should be a vector. Here is a description of the ...
160 views

### FindMinimum doesn't increase step size when necessary

I've spent much time finding a minimal example demonstrating this problem with FindMinimum. Normally one faces this problem when fitting very large and complicated ...
48 views

### Why does NSolve not solve this system of equations on a bounded domain? [duplicate]

I have three functions $E1,E2,E3$ of $t1$ and $t2$. The expressions are slightly complicated and involve trigonometric functions. For clarity purpose, they are given at the end of the question. I wan'...
91 views

### Round off in Mathematica Built-in functions [duplicate]

Is there a way to force Mathematica to use its Built-in functions instead basic functions? For instance, the Hypergeometric1F1[a,b,x] function has a exponential form when its firsts parameters are ...
43 views

### Evaluating Root forms in a Table [closed]

When I put a Root form in table, the parameters of the Root form don't evaluate. I don't know how I can indexed values substituted into root form in the table to get have numeric output. ...
512 views

### A problem about function N

Toady,I have a problem about N,described as below: For example N[1/3, 5] (* ==> 0.33333*) and ...
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### High Precision Plots of Eisenstein Series [closed]

When plotting the Eisenstein Series (great information here Eisenstein Series in Mathematica?) you observe highly non-trivial branch cut behavior close to the real axis. This makes the numerics break ...
4k views

### how to solve ODE with boundary at infinity

y''[x]-x y[x]==0 y[0]==AiryAi[0], y[infinity]==0 the analytic solution to this ODE is the Airy function y[x]=AiryAi[x] if I ...