Binomcoef function evaluation is not memoized and can take very long to run given large n

[zbenamram]

Description

Encountered an error when evoking binomcoef(n, k) with n = 20000, k=5. The process hangs at 100% cpu utilization.

Computational speed for this call can be increased with memoization.

Here is an example for how it could be implemented:
https://github.com/stevenbunting/stdlib/pull/2/files

Related Issues

Related issues # , # , and # .

Questions

No.

Demo

No response

Reproduction

binomialTest(5, 20000, {
    alpha: 0.05,
    p: 0.05,
    alternative: 'greater'
  });

Expected Results

To complete in a timely manner

Actual Results

Hangs indefinitely

Version

most recent

Environments

N/A

Browser Version

No response

Node.js / npm Version

No response

Platform

No response

Checklist

• Read and understood the Code of Conduct.
• Searched for existing issues and pull requests.

[stdlib-bot]

👋 Hi there! 👋

And thank you for opening your first issue! We will get back to you shortly. 🏃 💨

[kgryte]

@zbenamram Thank you for reporting this. We just pushed a patch to @stdlib/math/base/special/binomcoef. The issue ended up being an oversight in a recent refactoring. Namely, we were not leveraging symmetry. Commit: 6125c3c

Using the latest develop and running from the stdlib REPL, binomialTest now behaves as expected:

In [4]: binomialTest( 5, 2000, { 'alpha': 0.05, 'p': 0.05, 'alternative': 'greater' } )
Out[4]: {
  rejected: false,
  alpha: 0.05,
  pValue: 1,
  statistic: 0.0025,
  ci: [ 0.0009855751744273962, 1 ],
  nullValue: 0.05,
  alternative: 'greater',
  method: 'Exact binomial test',
  print: [Function: print]
}

If you are currently using the standalone packages (e.g., @stdlib/stats-binomial-test), the patch will not yet be available. We'll try to publish a new release of both the project and the standalone repositories in short order.

cc @Planeshifter

[Planeshifter]

@zbenamram As a follow-up, we released the patch for the standalone @stdlib/math-base-special-binomcoef package such that

var binomialTest = require( '@stdlib/stats-binomial-test' );
var out = binomialTest( 5, 20000, {
    alpha: 0.05,
    p: 0.05,
    alternative: 'greater'
});

will now work properly after re-installing dependencies.

[zbenamram]

Thank you so much! we are leveraging @stdlib/stats-binomial-test so we'll wait for that release. Thanks again for such a quick reply and resolution.

[kgryte]

@zbenamram You shouldn't need to wait for a new @stdlib/stats-binomial-test release. As we use semver, the latest version of @stdlib/math-base-special-binomcoef should be pulled in automatically upon a fresh install.