Math help[NA]

[Let'sgoflying!]

Known plots:
X=966 Y=8.54
X=1299 Y=7.87
I need an equation where I enter X each time to figure Y
Tks
Too many decades since I did this
Real world need, not hypothetical

 

[jimhorner]

Assuming a linear fit, 2 points only:

slope m = (y1 - y2)/(x1 - x2)

m = (8.54 - 7.87)/(966 - 1299) = -2.01e-3

y = mx + b => b = y - mx

choose any point:

b = 8.54 - (-2.01e-3 * 966) = 10.5

so y = -2.01e-3 x + 10.5

I've kept each of the calculated values to 3 sigdigs.

 

[Let'sgoflying!]

Yes linear

y = -2.01e-3 + 10.5

might need help with the
“ -2.01e-3 “

 

[kath]

-2.01e-3 is -0.00201

 

[eman1200]

the volume of a thick crust pizza with height "a" and radius "z" is π·(radius)2·(height), or pi*z*z*a.

also, I had pizza for dinner.

 

[jimhorner]

Yes linear

y = -2.01e-3 + 10.5

might need help with the
“ -2.01e-3 “

-0.00201

And I should have written:

y = -2.01e-3x + 10.5

I forgot the x when I orignally posted. It's corrected now


Sent from my iPhone using Tapatalk Pro

 

[nauga]

might need help with the
“ -2.01e-3 “

Rotate your phone 90 deg.

Nauga,
and his direction cosine matrix

 

[Half Fast]

Nauga,
and his direction cosine matrix

Try using quaternions instead. Less processing, and you’ll avoid gimbal lock.

Half-Fast,
Retired servo geek

 

[jimhorner]

Rotate your phone 90 deg.

Nauga,
and his direction cosine matrix

Or download pcalc. RPN!

 

[asicer]

Rotate your phone 90 deg.

Looks like a seagull flying over a lopsided pine tree...

 

[Rushie]

Rotate your phone 90 deg.

Nauga,
and his direction cosine matrix

I had my cell years before I figured that out.

 

[ColoPilot]

Assuming a linear fit, 2 points only:

I learned in college -- if you expect the results to be a straight line, only plot 2 points.

 

[Half Fast]

I learned in college -- if you expect the results to be a straight line, only plot 2 points.

I learned it as, “Two points define a line and three points don’t. Three points define a plane and four points don’t.”

 

[Let'sgoflying!]

Thanks!!

 

[Piperonca]

Regression made simple: https://en.m.wikipedia.org/wiki/Simple_linear_regression

 

[Piperonca]

FlyBy E6B (if you have an iPhone or iPad) has an interpolation function that you may want: http://www.skywritersoft.com/ios/flybye6b/flybye6biphone.html

Also available on Android: https://play.google.com/store/apps/details?id=skywritersoft.com.flybye6b&hl=en_US&gl=US

 

[Capt. Geoffrey Thorpe]

Go Matlab or go home.

 

[Piperonca]

Go Pylab for free

 

[nauga]

Go Matlab or go home.

[966 1;1299 1]\[8.84;7.87]

ETA a colon for a column vector.

Nauga,
from the geek farm

 

[Capt. Geoffrey Thorpe]

[966 1;1299 1]\[8.84 7.87]

Nauga,
from the geek farm

Error using \
Matrix dimensions must agree.

 

[Salty]

I learned it as, “Two points define a line and three points don’t. Three points define a plane and four points don’t.”

One point defines a line if the line is going directly away from you.

 

[Piperonca]

One point defines a line if the line is going directly away from you.

You make a good point.

 

[Bob Noel]

One point defines a line if the line is going directly away from you.

or if the line has zero length

 

[GaryM]

You make a good point.

I see what you did there.

 

[Piperonca]

Let's get this straight...don't want any pointless discussion, y'all hear?

 

[Half Fast]

You make a good point.

I think he’s just feeding us a line.

 

[Half Fast]

or if the line has zero length

That would be a segment. A line has infinite length.

 

[Piperonca]

A line has infinite length.

Kind of like this thread...

 

[ColoPilot]

Kind of like this thread...

Infinite length and no point

 

[Piperonca]

Folks, I think we’re done here. End of the line.

 

[Half Fast]

Folks, I think we’re done here. End of the line.

Thanks for the ray of hope.

 

[Pugs]

Or download pcalc. RPN!

Kids and their "software this and software that".

 

[Half Fast]

Kids and their "software this and software that".

Bought my HP-15C shortly after college graduation. It carried me through 36 years of engineering practice at Lockheed and it’s still going strong now that I’m doing pro bono stuff.

They don’t build ‘em like that anymore and that’s a real shame.

 

[Pugs]

Bought my HP-15C shortly after college graduation. It carried me through 36 years of engineering practice at Lockheed and it’s still going strong now that I’m doing pro bono stuff.

They don’t build ‘em like that anymore and that’s a real shame.

Bought this one in 1984 after my original 43C died. Still use it almost every day.

 

[nauga]

Error using \
Matrix dimensions must agree.

D'oh. Added a missing semicolon.

Nauga,
punctually

 

[Capt. Geoffrey Thorpe]

D'oh. Added a missing semicolon.

Nauga,
punctually

ans =

-0.0029
11.6539

 

[nauga]

ans =

-0.0029
11.6539

Oh FFS...(corrections in red)
[966 1;1299 1]\[8.54;7.87]

[966 1;1299 1]\[8.54;7.87]

ans =

   -0.0020
   10.4836

>>

Nauga,
who is better with Matlab than typing

 

[Rich Holt]

Kids and their "software this and software that".

Hey, I was a Kat!! Also, I have that patch in a frame on my wall.

 

[Rich Holt]

Photomath is the real answer to sleeping through math class. Point. Shoot. Solved.

 

[flyingbrit]

Yes linear

y = -2.01e-3 + 10.5

might need help with the
“ -2.01e-3 “

OP, e-3 means "times 10 to the -3 power", i.e. move the decimal point three places left. It became common with computers, which don't handle superscripts. IIRC, I first encountered this when using Lotus 1-2-3 in the 1980s. Here is a Wiki page which addresses this; look about 1/3 the way down:

https://en.wikipedia.org/wiki/Scientific_notation