JavaScript: Number.EPSILON and Number.MAX_SAFE_INTEGER

EPSILON The Number.EPSILON property represents the difference between 1 and the smallest floating point number greater than 1 > Number.EPSILON == Math.pow(2, -52) true Use Number.EPSILON to test floating point number equality. x = 0.2; y = 0.3; z = 0.1; equal = (Math.abs(x – y + z) < Number.EPSILON); MAX_SAFE_INTEGER & MIN_SAFE_INTEGER The MAX_SAFE_INTEGER constant has a …

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Non-cryptographic Hash Functions

See: List of non-cryptographic hash functions Pearson hashing Pearson hashing is a hash function designed for fast execution on processors with 8-bit registers. This hash function is a CBC-MAC that uses an 8-bit substitution cipher implemented via the substitution table. An 8-bit cipher has negligible cryptographic security, so the Pearson hash function is not cryptographically strong, but it is useful for implementing hash tables or as a data integrity check …

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$ cat from random import shuffle example_table = list(range(0, 256)) shuffle(example_table) def hash8(message, table): hash = len(message) % 256 for c in message: #hash = table[(hash+ord(c)) % 256] print(f’for c=\'{c}\’, ord(c)={ord(c)}: {hash} ^ {ord(c)} => {hash ^ ord(c)} and table[hash ^ ord(c)] = {table[hash ^ ord(c)]}’) hash = table[hash ^ ord(c)] return hash if …

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Bloom Filters in Redis

Probabilistic (P11C) data structure

AWS CDK Cheat Sheet

Documentation CDK Constructs Library TypeScript API Reference Best Practices Examples Some Gotchas When synthesizing an AWS CDK stack, I get the message –app is required either in command-line, in cdk.json or in ~/.cdk.json This message usually means that you …

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Downloading Files using Google Drive API

See: Google Cloud SDK (gcloud CLI) Create project in Enable Google Drive API in console Using gcloud cli: gcloud doesn’t provide command to access google drive. Install gdrive After entering verification code from browser: -q, –query <query> –order <sortOrder> OrderBy sets the optional parameter “orderBy”: A comma-separated list of sort keys. …

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Google Cloud SDK (gcloud CLI)

Installation options Home Brew: Official: gcloud CLI gcloud init – initialize or reinitialize gcloud See: gcloud auth – manage credentials  gcloud auth login – authorize gcloud to access Google Cloud Platform with Google user credentials gcloud auth list – lists credentialed accounts gcloud auth activate-service-account – authorize access to Google Cloud Platform …

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