September 2021

Bob

The topic is "BASIC using 1000-digit precision".

I used to use a Number-Theory version of BASIC many years ago. It could do all sorts of high-precision

calculations (not just factorising 200+ digit integers).

Unfortunately, it was a 16-bit package which now won't run on 64-bit Windows.

So, looking around for a suitable replacement, I came across "Decimal BASIC", from Japan.

The original program, co-incidentally, was also from Japan back in the 1990s.

The new one comes in a ONE Megabyte zipped package. Just Google "Decimal Basic Japan".

Then unzip it and point a shortcut to the BASIC.EXE program (no other installation required).

Here is a short program to display a few Fibonacci Numbers:

OPTION ARITHMETIC decimal_high

! Let Fib(-2) = -1 and Fib(-1) = 1. Then the first Fibonacci Number to be printed out is Fib(-1) + Fib(-2) = Fib(0)

LET f0 = -1

LET f1 = 1

for i = 0 to 20

LET f2 = f1 + f0

PRINT i;f2

LET f0=f1

LET f1=f2

next i

end

The other topic was the solution of this "simple" equation:

a / (b + c) + b / (a + c) + c / (a + b) = 4

where a, b and c are each positive integers.

Anyone can easily find (a, b, c) = (11, 4, -1) but these are not all positive.

The smallest positive answer, amazingly, is the 81-digit value for a,

namely: 154,476,802,­108,746,166,­441,951,315,­019,919,837,­485,664,325,­669,565,431,­700,026,634,­898,253,202,­035,277,999.

See the explanation in the 18m33s YouTube video by Mark Newman.

Solar powered weather station project from Alex :

-slave(remote) unit powered by 6V solar panel charging a 3.2V LiFePO4 battery (Bunnings clearance bin).

-Arduino Nano, INA219, BME280, thermistor sensor, nRF24L01+ radio

-Master unit is an ESP32, DS3231 RTC, nRF24L-1+ radio, SD card adapter, LCD display.

-code walkthrough of slave and master sketches.

-issues with multiple devices sharing the SPI bus. Solution was a p-chan mosfet enabling MISO line on CS active.

-issues with data structure type and size when communicating between different processor architectures.

-design approach to common code, error handling and sanity checks.

-charts plotted from collected data.

David planned to talk about the power supply made from the LM2576 chip or the wooden burr puzzle just finished using spacers and a saw sled on my table saw. We didn't get to the wooden puzzle - next meeting!

Martin gave an update on his robot design. Stepper motors & new wheels but still not enough torque? Controlled over the web with FWD, BACK, LEFT RIGHT and live video feed.

He also talked about a lipo battery bank with a battery management system.