Friday Night Maths

[Frozennova]

My brain is toast.

I have an equation I need to reverse to Solve both A & B, any care to school me?

((A*256)+B)/4 = 748

 

[bJN]

847 = 4\(B+(652*A))

 

[Diddums]

Yes, go get drunk like normal people.

 

[rhysduck]

847 = 4\(B+(652*A))

Edit: Damn beaten!

 

[Philtor]

My brain is now also toast having read that!

 

[MattTheTall77]

((A*256)+B)/4 = 748

((748*4)-B)/256=A

I think anyway, brain toasted as well today

 

[FoxEye]

24

 

[Frozennova]

847 = 4\(B+(652*A))

I didn't quite want it reversing that literally

((A*256)+B)/4 = 748

((748*4)-B)/256=A

I think anyway, brain toasted as well today

Ahh, I need to solve for Both A and B

Yes, go get drunk like normal people.

I would, buuuut I have a "customer" car on the dyno for tuning at 9AM

 

[MrRockliffe]

My brain is toast.

I have an equation I need to reverse, any care to school me?

((A*256)+B)/4 = 748

((748*4)-B)/A = 256

 

[Russinating]

((A*256)+B)/4 = 748
(A*256)+B = 2992
A*256 = 2992-B
A = (2992-B)/256
B = 2992-(A*256)

If B = 1 then A = 11.68359375

My maths is ***** but do you not need to know at least one of A or B to find the other?

 

[dowie]

My brain is toast.

I have an equation I need to reverse to Solve both A & B, any care to school me?

((A*256)+B)/4 = 748

You might want to explain what you're trying to do here OP - give some context or further details etc...

You've got two unknown variables so currently, without any other conditions, they there are infinite values they can take.. for example when B is 0 A is 11.6875 and when A is zero B is 2992.

If you want to illustrate this then, with A on the x axis and B on the y axis, if you were to draw a line passing through (0, 2992) and (11.6875, 0) any point along that line gives you a value for A and B

 

[dowie]

My maths is ***** but do you not need to know at least one of A or B to find the other?

If you've got another equation involving A and B then you're good. Think back to simultaneous equations at school - if you've got two equations with the two unknowns then you can substitute in and solve for one of the variables etc... If you plot both lines you're basically finding the intercept.

 

[Frozennova]

I think I may have solved it from a mathematically concept. Just trying to confirm try the maths on a few inputs ...Not quite for the application

You might want to explain what you're trying to do here OP - give some context or further details etc...

You've got two unknown variables so currently, without any other conditions, they there are infinite values they can take.. for example when B is 0 A is 11.6875 and when A is zero B is 2992.

If you want to illustrate this then, with A on the x axis and B on the y axis, if you were to draw a line passing through (0, 2992) and (11.6875, 0) any point along that line gives you a value for A and B

Sending data over a serial like protocol that deals with hexadecimal. The receiving device performs the formula in the OP to convert the data it receives to a real value.

All of the values must be integers (non-decimal)

 

[MattTheTall77]

((A*256)+B)/4 = 748

if A=11 (can't be over 11 round number otherwise it is over 748*4 so can't add B) based on the earlier 11.68359375

((11*256)+B)/4 = 748

2816+B = 2992

b = 2992 - 2816 = 176

b=176, a=11 seems to work .

 

[PiKe]

B is 176 and A is 11

I did 748 * 4

Then 2992 divided by 256 which was 11.something

So I then assumed that A was 11 and then took the difference from 2992 to give me B.

 

[Frozennova]

((A*256)+B)/4 = 748

if A=11 (can't be over 11 round number otherwise it is over 748*4 so can't add B) based on the earlier 11.68359375

((11*256)+B)/4 = 748

2816+B = 2992

b = 2992 - 2816 = 176

b=176, a=11 seems to work .

Thanks,

That's how I got there too

 

[dowie]

All of the values must be integers (non-decimal)

Do they need to be positive? Non-zero? That might narrow it down a bit too...

Currently you still have a bunch of possible answers

A = 0, A = 1, A = 2 etc.. all give you integer values for B

 

[Frozennova]

Do they need to be positive? Non-zero? That might narrow it down a bit too...

Currently you still have a bunch of possible answers

A = 0, A = 1, A = 2 etc.. all give you integer values for B

Mentioning hex wasn't clear enough. Neither A or B can be greater than 255

 

[Chojin]

((A*256)+B)/4 = 748
((A*256)+B) = 748 * 4 = 2992
2992 mod 256 = 176 (B)
(2992 - 176) / 256 = 11 (A)

 

[Minusorange]

((A*256)+B)/4 = 748
(A*256)+B = 748 *4
(A*256) = (748 *4) - B

A=X
B=Y