Hello, I am Laszlo

An approach to Walsh pais with SIMD

11/19/2023

In a previous posts I looked into using Single instruction, multiple data, SIMD to find the Median value in a sample integers.

The definition of median in case of

• an odd sample size, find 'middle' element of the ordered samples.

• an even sample size, find the 2 elements in the middle of an ordered sample size, and calculate the average of those.

I have recently came across a blog post from Andrey Akinshin proposing to benefits of using Hodges-Lehmann location estimator to calculate a pseudo median.

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An approach to 95th Percentile with SIMD

11/05/2023

Introduction

In a previous post I looked into using Single instruction, multiple data, SIMD to Sum an array of integer elements and to find the Median value of sample.

When working with statistical data, we often need to find the 95th percentile element of a sample. Calculating the Sum is useful for finding the mean value but finding the 95th percentile element requires a different approach. However, the P95 algorithm is similar to the way the Median element is found.

The 95th percentile is a statistical term that means the value below which 95% of the data in a given set is found. For example, if you have a set of test scores, the 95th percentile score is the one that is higher than 95% of the other scores. You can calculate the 95th percentile using this formula: n = (P/100) x N, where P = percentile, N = number of values in the data set, and n = ordinal rank of the given set. The 95th percentile is often used to measure service response times, as it allows for burstable usage patterns.

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An approach to median with SIMD

10/28/2023

Introduction

In a previous post I looked into using Single instruction, multiple data, SIMD to Sum an array of integer elements.

When working with statistical data, we often need to find the mean/median element of a sample. Calculating the Sum is useful for finding the mean value, but finding the median element requires a different approach.

The definition of median in case of

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CHttp Visual Studio Code Extension

10/20/2023

I have been recently working on CHttp which is a tool to send HTTP requests and to measure the performance of REST APIs.

The primary goal of the tool is the ability to measure GET HTTP requests using version HTTP/2 and HTTP/3. As the tool is based on .NET (currently version 8), it requires a reasonably up-to-date Windows installation or the libmsquic package in case of Linux.

The standalone tool can be installed from GitHub, as a dotnet tool by using the dotnet tool install -g LaDeak.CHttp command or by as a Visual Studio Code Extension.

Using CHttp Visual Studio Code Extension

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Sum with SIMD

10/07/2023

One of my projects requires to calculate an average over about a hundred integer values. These values are available in an array, I used the Sum extension method from Linq to calculate the sum of them.

I have learned two things about this method:

• With the current version of .NET, it does seem to use vectorization to calculate the sum of items.

• It uses checked arithmetic, meaning that it throws an exception in case of an overflow.

This is the (optimized) assembly code generated by the JIT for the Sum method:

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