248 views

Underflow error General::munfl from E^x instead of Exp[x]

In contrast to earlier versions, Mathematica 11.3 and 12.0 generate lots of underflow errors from my code, e.g. ...
552 views

NDSolve DAE with Constraints

I'm trying to make some numerical simulation with NDSolve. I have encountered a few problems. Here is a simplified version of the equations: ...
508 views

DSolve with SetOptions[Solve, Method -> Reduce] Behaving Differently in Ver 11.1.1

With version "11.1.1 for Microsoft Windows (64-bit) (April 18, 2017)", DSolve[{SI'[s] == Sin[PH[s]] , PH'[s] == Sin[SI[s]]/e}, {SI[s], PH[s]}, s] produces the ...
694 views

Why does 1 - Exp[-10.0^12] cause an out-of-memory error?

I would like to understand why evaluation of the expression 1 - Exp[-10.0^12] causes an out-of-memory error and how can I prevent such errors when calculating ...
709 views

SetOptions locally?

Is there a way to SetOptions locally? For example, I have a Module and inside it I am doing a lot of ...
231 views

Change lighting in ChromaticityPlot3D

It looks to me like ChromaticityPlot3D has some default lighting, but unlike most Graphics3D functions the Lighting option doesn't seem to have any effect. However, the documentation states "...
2k views

Machine precision near zero: not fulfilled?

I am puzzled by the behavior of Mathematica machine precision with numbers approaching zero. This manifests itself, e.g., with FixedPoint and the like. In the ...
551 views

Why does DSolve return two solutions for my ODE?

I wanted to solve the differential equation: $y’ = (1+2x)\sqrt{y}$ with $y(0) = 1$. It can be done by hand, and to check my answer I typed the following in Mathematica ...
286 views

Slow exponential evaluation over lists

This question,which is still unanswered, might be relevant because it involves NIntegrate over lists and it also has Exp. In ...
175 views

Change system options in package

I use Mathematica mostly for numerical calculations, and sometimes the performance of numerical calculations can be greatly improved if the high-precision arithmetic can be switched off by ...
131 views

Can I force Mathematica to use machine precision? [duplicate]

Some built-in functions (like Exp) give an arbitrary precision result, even when the argument is a machine precision number. Example: ...
101 views

Calculating eigensystem of a matrix containing very small numbers [duplicate]

I'm dealing with a matrix containing very small numbers like 10^(-370). When I compute the eigensystem of my matrix, it takes too much time, though the matrix size is not large. Can anyone explain ...
758 views

Product of elements of a list

Sum is for functions; Total is for a list. Product is for a function; what is the command ...
I have the following expression. It's based on the negative-log-likelihood of a Poisson-Gaussian noise model, i.e. a convolution of a Poisson & Normal distribution. The value $x_{i}$ is the ...