- #1
cryforhelp104
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- TL;DR Summary
- What does a lower case r mean over variables in an equation?
I've attached an example here.
What does a lower case r mean over variables in an equation?
In summary, a lowercase r over variables in an equation typically denotes a specific type of relationship or function, often indicating a variable that is a reference, reduced form, or a particular statistical measure like correlation. The context in which it appears can clarify its precise meaning, but it generally signifies a modification or a particular attribute of the variable it accompanies.
I've attached an example here.
- #2
jedishrfu
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Can you provide some context like what book you found this notation or in what topic the equation is used?
- #3
FactChecker
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I am not familiar with that as a common notation. The book or article should define that notation someplace before it is used. It is not uncommon for me to have to scan back through the text looking for a notation definition. If you are lucky, there might be a section where all notation is defined.
- #4
cryforhelp104
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Hi, I attached a photo above. I've re-attached it herejedishrfu said:
- #5
cryforhelp104
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Unfortunately, the notation is from a power point and has no references.FactChecker said:
- #6
jedishrfu
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When we ask for context, we mean some reference either a mathematical field like geometric calculus or a book where’s it’s used Or the problem in which it was used.
Did this come up in a discussion for a new battery technology? What does the script E stand for? Electromotive force? Is the R some sort of battery resistance?
Could this be some kind of directional derivative along a position vector R or does R represent the real number system?
There is no way to help you here without some context.
Your reluctance implies this is some sort of privileged information from either a company or government source and you can’t divulge that if so then there’s nothing more to do here.
I’ve searched several places and have come up with nothing of note so we are at a dead end without context.
Lastly, please don’t give out any corporate confidential or classified information here.
My suggestion is to go ask the PowerPoint presenter what it means.
Did this come up in a discussion for a new battery technology? What does the script E stand for? Electromotive force? Is the R some sort of battery resistance?
Could this be some kind of directional derivative along a position vector R or does R represent the real number system?
There is no way to help you here without some context.
Your reluctance implies this is some sort of privileged information from either a company or government source and you can’t divulge that if so then there’s nothing more to do here.
I’ve searched several places and have come up with nothing of note so we are at a dead end without context.
Lastly, please don’t give out any corporate confidential or classified information here.
My suggestion is to go ask the PowerPoint presenter what it means.
- #7
cryforhelp104
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Dude... it's one of Maxwell's equations. This is from a publicly available slide in my modern physics lecture. The E script stands for the electric field. The powerpoint doesn't have references. The link to the publicly available powerpoint is here. It's on slide 25.jedishrfu said:
- #8
jedishrfu
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They start to use the notation on slide 7 without any description.
from the F=ma equation it looks like it’s just saying the F is a vector function.
maybe they couldn’t place vector arrow notation on the vector quantities and so used an R instead.
from the F=ma equation it looks like it’s just saying the F is a vector function.
maybe they couldn’t place vector arrow notation on the vector quantities and so used an R instead.
- #9
Mark44
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It would have been good to tell us this, dude.cryforhelp104 said:
The 'r' characters in the image are an artifact of copying from the PowerPoint deck. They are supposed to be arrows that signify vectors. The characters aren't present in the original deck.cryforhelp104 said:
Here's how the image originally appeared.
The same problem appears on slide 7 of the deck.
- #10
- #11
Mark44
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From the link that the OP showed.jedishrfu said:
cryforhelp104 said:
- #12
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Dude, lose the 'tude!cryforhelp104 said:
I downloaded the file in question, and guess what? The r's turned into little overhead vector arrows.
And had you posted this link in the OP rather than play the game "Tell the people on PF as little as possible and make them guess" you would have had your answer in an hour and not a day.
Dude.
- #13
berkeman
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Thread paused pending Moderation...
(biting my lip)
(biting my lip)
- #14
