The Kernel is the back-end application thread that does the actual evaluation of all non-graphical expressions. It can be accessed directly through the console but is more commonly working behind the scenes to power the Notebook Interface. Multiple Kernels may be run for parallel computation.

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42
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5answers
20k views

How do I clear all user defined symbols?

Is there some way to do this other than going to Evaluation -> Quit kernel and firing a new one up?
39
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4answers
5k views

Saving data inside a notebook so that I don't have to run it again?

Piggybacking on this, I am somehow not fully convinced that I can't save data generated by a calculation in a mathematica file so that when I re-launch said file, I wouldn't have to run my ...
37
votes
4answers
2k views

Aborting evaluation when the memory exceeds a certain limit

Sometimes when generating a lot of data the memory usage shoots beyond its physical realm and my laptop freezes. There is no way to stop Mathematica when this happens. Task manager (or its equivalent ...
33
votes
2answers
2k views

What information is sent to Wolfram Research when loading or working with Mathematica?

Recently I am told that information unknown to the user is sent to Wolfram Servers. Is there any truth behind it ? I was told that more than just an IP address of the user is sent to them and that ...
30
votes
3answers
368 views

How can I evaluate untrusted Mathematica code in a sandbox?

Is there any way to build a sandbox to evaluate untrusted Mathematica expressions in order to prevent them from having (malicious or accidental) harmful side effects? Context: I'm developing a system ...
26
votes
1answer
871 views

Why are there two separate MathKernel processes running when I start up Mathematica 9?

When I start the Mathematica 9 Front End, and check the list of running processes, I see two separate MathKernel processes. If I only start the kernel, without a front end, then there's only one ...
24
votes
2answers
1k views

Kernel crash after idle in version 10.0

Bug introduced in 10.0.0 and fixed in 10.0.2 In version 10.0, when I leave the Mathematica section idle for some time (of order an hour), the kernel quit automatically. The syntax highlighting is ...
21
votes
2answers
3k views

Unsaved notebook is crashing: is there any way I can save the state of the MathKernel before I kill it?

So I'm in the middle of generating some plots and all of the sudden the frontend goes dead and I haven't saved my work. I'm using Mathematica 8 in MacOS X. The MathKernel process is still running and ...
17
votes
2answers
411 views

MathKernel doesn't return all Messages

In Mathematica I run this command: Plot[Sin[x], {x, 1, 15}, GridLines -> error] It generates a Plot with this error message: A GridLines specification ...
17
votes
1answer
566 views

Quit the Kernel and start new session automatically

The question is how to quit the kernel, start a new session automatically, and to be able to run such procedure from e.g. Button. This is especially useful when ...
16
votes
2answers
900 views

How to restart computation when kernels die?

When an important process needs to be kept alive, there are monitoring tools to restart them if they die (e.g. god tasks in ruby), in my case I have an overnight scraping task that I need to have done ...
16
votes
1answer
203 views

How to connect to EC2?

I have Mathematica 10.2 installed on an Ubuntu 14 machine in Amazon web services's elastic computer cloud. I have dido access and I'm connected to the instance though ssh on the terminal. I have an ...
15
votes
4answers
4k views

When running Mathematica from a Linux terminal, how can I prevent a script from terminating upon logout?

I am running Mathematica on a remote Linux cluster, by the terminal, using the math command. (I do not have access to a terminal GUI. For example, when I type the ...
15
votes
2answers
298 views

How can I access a variable in one evaluator from another evaluator?

I have two notebooks, each with a different kernel. Is there a way to grab the value of a variable in KernelA from KernelB?
14
votes
1answer
1k views

Kernel Management

I would like to run a computation in one NoteBook that will take 2 hours. Could I assign this Notebook a specific Kernel so I can run computation in other Notebooks ?
14
votes
1answer
714 views

Space-efficient null space of sparse array

I have a roughly 100,000 × 3,000 matrix (as a SparseArray) that I'd like to find the kernel (null space) of. It has about 500,000 nonzero entries, all -1 or 1. ...
13
votes
2answers
368 views

ScheduledTask with scoped variables. Working with timed evaluation

I guess I have to try harder and focus more but timed evaluation always frustrates me. I will show the issue on simple example of delayed trigger. ...
13
votes
2answers
1k views

Automatically load packages at startup

I'm a physics student and I try to simplify my day with Mathematica. Every time I use Mathematica I need Div[], Grad[], ...
13
votes
1answer
154 views

All value types for a symbol?

Robby Villegas here shows a nice way to see all the types associated with a symbol. He sets a symbol, valueTypes, to an explicit list of the values types in ...
12
votes
3answers
342 views

Suspecting bug in Parallel Framework

I've reduced my actual problem to: ParallelEvaluate[ Module[{slot=1}, Slot[slot] ] ] gives error messages that I think shouldn't be there. It seems I can ...
12
votes
3answers
449 views

Handling Kernel quit

One can use $Epilog to do something when the Kernel is quit or put an end.m file next to the ...
11
votes
1answer
458 views

Kernel crashes when plotting $z=\sqrt{(x^2 + y^2)}^0$

Bug introduced in 7.0.1 or earlier and fixed in 10.0.1 I'm plotting a 3D function, which makes Mathematica V9 (running on Windows 7) crash all the time. Does this only happen for me or for somebody ...
11
votes
1answer
1k views

Scheduling Mathematica scripts to run from a command line [duplicate]

I want to run Mathematica "jobs" on a daily/weekly basis to do system maintenance and as part of daily processing operations. What is the best way to do this?
11
votes
2answers
761 views

Evaluator option for Mathematica Scripts

I have mathematica with many additional kernels besides Local ( e.g., core1, core2, core3, core4 ... ) added through Kernel Configuration Options. I have been running multiple copies of a simulation ...
11
votes
1answer
116 views

How to clean up temporary files when the kernel exits?

There are Mathematica packages that must create temporary files to function. If we are implementing such a package ourselves, how can we ensure that the temporary files will get cleaned up when the ...
10
votes
2answers
392 views

Why LibraryLink function crashes at a second time?

Bug introduced in 9.0 or earlier and fixed in 10.3 Update As Todd Gayley commented under halirutan's answer, this is a bug. I'm trying link one of Lapack's function to Mathematica through ...
10
votes
2answers
301 views

Return partial result when MemoryConstrained aborts NDSolve

I use NDSolve to solve a large set (~400) of coupled ODEs. Sometimes, the memory (~4GB) gets filled up, and my computer becomes impossible to work with, because it ...
9
votes
2answers
369 views

Seeking strategies to deploy a function securely without a front end

Background I have a fuction, which calculates an analytic solution to a multi-dimentional geometry problem. The function takes a list of real numbers (typically less than a dozen) and outputs a ...
9
votes
2answers
331 views

Does Mathematica on Mac OS use virtualization for certain functions?

I'm evaluating this code in Mathematica 8.0.0 on Mac OS X 10.6.8: ...
9
votes
1answer
1k views

How to stop the Kernel from running wild?

How to abort or stop this (accidently large defined) SparseArray production? s = N[SparseArray[Table[{2^i, 4} -> i, {i, 30}]]] Alt+. or Alt+, seem to give ...
9
votes
2answers
888 views

Keep MathKernel Running In Background - Speed Up Execution Time

Background: I'm running Debian on a remote server with Mathematica installed. I have several dozen small mathematica files that are run in cron jobs at unpredictable intervals and updated based on a ...
8
votes
2answers
276 views

Difference between Evaluation>>Quit Kernel and Quit[]

What is the difference between Evaluation >> QuitKernel and Quit[]? Both seem to quit the kernel (and clearing all ...
8
votes
2answers
188 views

Obtain input expression from history without evaluating

I typed and evaluated an expression, but deleted it from the notebook. For instance, suppose it was In[1]:= Round@SessionTime[] Out[1]= 2 I now want to retrieve ...
8
votes
3answers
2k views

Generating figures over remote connection (using terminal)

Recently I've been making movies by having Mathematica create figures and then I combine all of them together using ffmpeg. The problem now is that my macbook is ...
8
votes
1answer
202 views

Why am I getting a kernel crash on Chop?

Solve bug (see answer) introduced in 9.0 and persisting through 10.2.0 First post, hopefully I figure out the formatting easily. Please forgive me if this posts ...
8
votes
2answers
789 views

Using NotebookDirectory in batch-mode

I am running Mathematica via the terminal (Linux) and my .m-script contains the command: ...
8
votes
1answer
91 views

Launch Front End from .NET MathKernel and return result to .NET

Is it possible to launch a front end and open a notebook from a .NETLink kernel and return a result from the notebook to .NET? In the code below "x" appears in the .NET textbox after 10 seconds but ...
8
votes
1answer
622 views

The most simple Manipulate freeze the notebook on v10.1

I realize this won't be a particularly clear question. As I'm not able myself to find a pattern for the problem I'm talking about I won't be able to give enough informations to make it fully ...
8
votes
0answers
94 views

How to prevent the kernel from exiting when a LibraryLink function segfaults?

I do realize that this might be controversial, but I believe I have a real need for it this time. If a process tries to access memory at a location it doesn't own, it will by default exit with a ...
8
votes
0answers
139 views

How to write crash-robust code?

When a notebook crashes all the work I was doing is lost - I'd like to ameliorate this situation! Is there a way to decorate a symbol so that it is saved to disk whenever it changes, or after a ...
8
votes
0answers
473 views

Keyboard issues with Mathematica 9.0.1 for Linux [closed]

After working for a while with Manipulate function and increasing the number of variables to be manipulated, keyboard stops working properly in the Notebook. It ...
7
votes
1answer
334 views

CompilationTarget->“C” crashes the kernel

Major deviation from my original post I realize that the long code I originally had was very discouraging to debug and did not attract any answers. So I have decided to revamp this question ...
7
votes
1answer
4k views

Is there a system Reset? [duplicate]

Possible Duplicate: How do I clear all user defined symbols? The normal way I reset the Mathematica kernel to its initial state is through the notebook interface: ...
7
votes
1answer
161 views

ClearAll[“Global`*”] stops working with Context set to 'unique to this Notebook'

I just changed my default notebook context to 'unique to this Notebook' so that variables don't roll across numerous open notebooks. Doing this, however, made the command ClearAll["Global*"] stop ...
7
votes
1answer
210 views

Importing parts of Packages

Some programming languages offer the possibility of importing a single function from a library, as in from x import y I'm looking to import only one function ...
7
votes
2answers
317 views

Communication between local kernels

this is my first post but you have already helped me so many times that I have to start by saying thanks a lot! I have a really long calculation to do, and I have used the Evaluation->Kernel ...
7
votes
1answer
152 views

Why can't I abort main evaluation from ScheduledTasks (Service Link)?

FrontEndExecute[FrontEndToken["EvaluatorAbort"]] is equivalent of the menu item: Evaluation >> Abort. It works with ...
7
votes
1answer
2k views

Improving NDSolve speed for heavily stiff problems

Having looked around the intergoogles and Mathematica.SE, I thought I'd pose a question with a minimum working example. Here is the situation I am trying to improve: I am solving a 4th order non ...
7
votes
1answer
817 views

Creating and editing new stylesheets

I'm trying to create a stylesheet, but the process has become painful. I'm sure that this has to do something with resetting something in Mathematica everytime I make changes to the stylesheet. To ...
7
votes
0answers
2k views

Threads vs Cores: How many kernels need to launch in parallel Mathematica?

I have a dual-core intel machine. I would like to test how many parallel local kernels should be launch to get the optimized performance. Knowing that the HyperThreading technology of Intel could run ...