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Questions tagged [math]

Abstract study of of topics such as quantity (numbers), structure, space, and change.

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3 votes
0 answers
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Reverse engineering a predictive model with lots of example inputs/outputs

I'm working on a project to approximate an existing model that generates prices for an asset given a large number of input variables. The model comes with ~1,000 unique example lines in batches of ...
JackIC155's user avatar
1 vote
1 answer
84 views

What was the original math operation after optimizing compiler?

I'm pretty sure that original code was much simpler: (((x + 16) >> 31) ^ abs(x + 16) & 3) + 4 * ((y + 16) % 4) - ((x + 16) >> 31) Looks like division with remainder... Any ideas what ...
mastermind's user avatar
2 votes
1 answer
104 views

Overclock CPU in BIOS - ARM/C/C++/Py

new guy here. Working on Bi0S script, adding as many features as possible. It is possible to change fan speeds, advanced security, manipulate voltages, etc. How do you overclock the microprocessor ...
Calculus Lui YaleTessy's user avatar
1 vote
1 answer
103 views

Turning very complicated arithmetic and reverse engineered check into useable code in C#

so I have this problem of me not understanding how to convert this one function into useable code in C#. Problem being that I am currently hooking into a game via C# and I want to rebuild a function ...
Oliver Vedel Rasmussen's user avatar
2 votes
0 answers
44 views

Calculator shows incorrect result for 32-bit subtraction?

I was trying to argue about the operation of a routine called micros() and millis() that is used on the Arduino platform, and I ended up finding this calculator. The calculator shows a different ...
R R's user avatar
  • 21
1 vote
0 answers
41 views

It does not appear to be a standard CRC. Can I know this formula in reverse?

Interpreting binary protocols for older equipment. I interpreted most of the contents of the protocol, but the last error detection part seems to be in crc16 form, but it does not seem to be standard. ...
EPIS_'s user avatar
  • 11
1 vote
2 answers
204 views

Identifying rating algorithm

I'm trying to identify the rating algorithm used to calculate the displayed average of a 1 star to 5 stars rating system. To analyze the data I collated the first and last 1000 ranks and added the ...
madlen's user avatar
  • 11
3 votes
1 answer
172 views

Construct a number from 0-999.9 using 5 data bytes of a MIDI SysEx message

I'm sending MIDI messages to a proprietary turntable that has an LCD screen on it. The normal software sends out updates via MIDI SysEx to display the current tempo on the LCD. The MIDI is being ...
chason's user avatar
  • 33
3 votes
2 answers
639 views

What is the purpose of consecutive ADC instructions to a single register?

To clarify, I understand how ADC works. It's the same as a regular ADD but with an extra 1 if the Carry Flag was set. Its use in the snippet below makes perfect sense to me since an overflow is most ...
Nux's user avatar
  • 133
4 votes
1 answer
374 views

Need help understanding a complex mathematical password checking function?

Below is a complex pseudocode for a mathematical problem which attempts to check if a password entered is correct or not. Previous Analysis Done: Data is arranged in the form of 3x3 Matrix with i,j ...
Sujith Sizon's user avatar
4 votes
2 answers
262 views

Generating a key for a simple algorithm

I have this pseudo code: v5 = serial[6] + serial[0] - serial[7] - serial[2]; LOBYTE(v5) = serial[1]; v8 = serial[3] + v5 - serial[4]; if ( v8 != serial[5] ) goto FAIL; The variable serial[] is ...
0x3h's user avatar
  • 41
-2 votes
1 answer
71 views

Area calculations & what about 12.5m? [closed]

The shown girder is made from plain stone concrete and four 25 mm diameter steel wires. Including the weight of steel wires, determine self weight of the girder if its length is 12.5 m. Neglect the ...
Just Believe 's user avatar
2 votes
1 answer
122 views

Need help to figure out a chksum [closed]

I am looking at a 32 byte sequence, the chksum I believe is either the 1st two bytes or last 2 bytes (I am leaning on the last 2 bytes). I think it is a straight 16bit xor but I can't find the crunch ...
JGizmo's user avatar
  • 21