[Mil MYS-8MMX] Mil MYS-8MMQ6-8E2D-180-C Application 1 - Calculate pi

tobot

[Mil MYS-8MMX] Mil MYS-8MMQ6-8E2D-180-C Application 1 - Calculate pi [Copy link]

We know that pi is an infinite non-repeating decimal (also called an irrational number). Sometimes we can use the time to calculate the value of pi to measure the quality of the CPU . Seeing that netizen @MianJi likes to compare this evaluation board with the Raspberry Pi 3B , I'd like to join in the fun. I have a ready-made Raspberry Pi 3B and 4B , but they are both 1G versions. Their performance may not be lower than that of the i.MX8M Mini , but the difference in memory may make them suffer a little in the evaluation results.

In the original ecosystem of Mil MYS-8MMQ6-8E2D-180-C , there are only python2 and python3 . Even the most commonly used gcc is not found. There is nothing like java , ruby , go , php ... However, there is bc in the shell , you can try it, then let's mainly use python for comparison.

Here are several calculation methods:

1. Power series expansion of inverse trigonometric functions

We know that π is a very special value in trigonometric functions , such as sin( π /2)=1 , tan( π /4)=1 , etc. Therefore, we can use the power series expansion of inverse sine or inverse tangent to calculate the value of pi .

For example,

In the inverse cotangent formula, let x = 1 , then arctan(x) = π /4 , expand and organize

Compilation Tools	Order	Cycle times	Raspberry Pi 3 B	Raspberry Pi 4 B (1G)	MYS-8MMX
shell	time bash trigonometric.sh	10000
bc	time bc -q trigonometric.bc	1 0000000
python2	time python 2 trigonometric.py	5 0000000
python3	time python 3 trigonometric.py	5 0000000

2. Grid method

The distance from a point inside a circle to the center of the circle is less than the radius of the circle. So divide 1/4 of the circle into n*n grids, count how many grids fall inside the circle, divide it by the total number of grids, and multiply by 4 , and you can calculate the value of π.

Compilation Tools	Order	Cycle times	Raspberry Pi 3 B	Raspberry Pi 4 B (1G)	MYS-8MMX
shell	time bash grid.sh	10000
bc	time bc -q grid.bc	10000000
python2	time python 2 grid.py	5 0000000
python3	time python 3 grid.py	5 0000000

3. Multiplication

Pi can be calculated using

.

Compilation Tools	Order	Cycle times	Raspberry Pi 3B	Raspberry Pi 4 B (1G)	MYS-8MMX
shell	time bash multipli.sh	10000
bc	time bc -q multipli.bc	5000000
python2	time python 2 multipli.py	50000000
python3	time python 3 multipli.py	50000000

4. Monte Carlo method (random number method)

The method of estimating parameters using the results obtained through probability experiments is called the Monte Carlo method .

We can randomly pick a point in the square and the probability that it is in its inscribed circle is π /4 . We can use this to calculate pi.

Compilation Tools	Order	Cycle times	Raspberry Pi 3B	Raspberry Pi 4 B (1G)	MYS-8MMX
shell	time bash rand.sh	1000000
python2	time python 2 rand.py	50000000
python3	time python 3 rand.py	50000000

Judging from the above results, the performance of NXP 's i.MX8M Mini is slightly lower than Broadcom BCM2711 , but higher than Broadcom BCM2837 .

Why does memory overflow occur?

tobot

Source code, share it!

pi-used.rar (2.49 KB, downloads: 0)

2021-8-11 10:22 上传

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freebsder

This is quite interesting. It seems that the numerical calculation of imx8 is still a bit weak. After all, it came out a few years later.

hqli126

The performance of i.MX8M Mini is slightly lower than Broadcom BCM2711 and higher than Broadcom BCM2837