Biggest science or math pet peeve

[Borg]

Who'da thunk it... ? [COLOR=#black]..[/COLOR] [COLOR=#black]..[/COLOR]

Wow. I've always been careful with using parenthesis on calculators but that is odd.

 

[sophiecentaur]

Who'da thunk it... ? [COLOR=#black]..[/COLOR] [COLOR=#black]..[/COLOR]

I wouldn't have assumed it but it isn't surprising for a device with a certain amount of brain. I would always have put in the parentheses. The first proper calculator I used was an HP and Reverse Polish is still my automatic approach to calculations on a calculator with anything ambiguous about them. You can't go wrong with RPN (haha). It's good to know that the Scientific Calculator could store the whole expression before evaluating it. I wonder how long the expression would have to be to beat it.

 

[PeroK]

Wow. I've always been careful with using parenthesis on calculators but that is odd.

A possible explanation is that the average person using the normal calculator would never have heard of PEMDAS and expect those operations to be done left to right. This is the way it works in those arithmetic puzzles in the newpapers (where they do actually say: operations to be carried out left to right).

But, for people using the scientific calculator the dark cloud of PEMDAS hangs over them, so the operations are carried out in a bizarre order.

 

[sophiecentaur]

But, for people using the scientific calculator the dark cloud of PEMDAS hangs over them, so the operations are carried out in a bizarre order.

Not really "bizarre". It's just following the rules for the shorthand way of writing down a calculation. It's 'grammar' for Maths.
I never trust myself with a long chain of key entries with no visual feedback, in any case. I like to write the expression down so I can see what I have done and then leave it to the processor to work it out. I was in a pub the other day and the barmaid got three different answers on three attempts on a hand calculator. I sympathised.

 

[PeroK]

Not really "bizarre". It's just following the rules for the shorthand way of writing down a calculation. It's 'grammar' for Maths.
I never trust myself with a long chain of key entries with no visual feedback, in any case. I like to write the expression down so I can see what I have done and then leave it to the processor to work it out. I was in a pub the other day and the barmaid got three different answers on three attempts on a hand calculator. I sympathised.

It isn't really grammar for mathematics, it's grammar for certain arithmetic expressions that you never actually need. I did a degree in maths and have been studying maths and physics for 3 years now. I have no idea what PEMDAS really says and I've never found the need. No one uses these expressions outside of arithmetic classes to teach the rules of PEMDAS!

Still peeved!

The symbols ##\times## and ##\div## are not used in "proper" maths in any case. So, there need be no rules to govern their usage.

 

[PeroK]

This is my last post on the subject! And it's a serious one.

PEMDAS encourages students not to use brackets, but to rely on a convention that everyone else may or may not know exactly. This continues into their maths generally, so you see things like:

##\sin x + y##

This is partly the influence of teaching PEMDAS.

If, instead of PEMDAS, they were taught the importance of avoiding ambiguity in mathematics, this would be much better. And that is genuinely important to maths at all levels. They should be taught to use brackets whenever there is any room for ambiguity. The relevance of PEMDAS is short-lived and it teaches bad habits that are then much longer lived.

 

[DrClaude]

And, in fact, homework posters on this forum often leave out brackets. What do the homework helpers do?

And units. Which is a pet peeve of mine: not using units.

 

[ZapperZ]

Could be a common wrong definition or an ineffient way to solve a certain equation. I don't know, what in science and math bugs you? Educators should fill this thread! :D

Coming back to the original question of the thread, one of my biggest pet peeve is when I hear a non-scientist tells me "it's ONLY a theory!"

Zz.

 

[ZapperZ]

And units. Which is a pet peeve of mine: not using units.

Oooh... then you might want to bake a banana bread! :)

Zz.

 

[fresh_42]

Oooh... then you might want to bake a banana bread! :)

Zz.

I prefer trees. It's my favorite response to an answer like: "5" - "5? 5 trees, or what?"

 

[fresh_42]

And units. Which is a pet peeve of mine: not using units.

Meanwhile I think, this must be actually a disease, like dyslexia or dyscalculia. Maybe, it's a hope of mine.

 

[Mark44]

I prefer trees. It's my favorite response to an answer like: "5" - "5? 5 trees, or what?"

So, ##\log_2 32 = 5 \text{ trees ?}##

 

[S.G. Janssens]

Maybe it is a good idea to stipulate in the homework template that problems may only be posted in non-dimensionalized form .

 

[sophiecentaur]

I have no idea what PEMDAS really says and I've never found the need.

Ahh, that's where you are wrong my boy.
3p+2q makes sense to you, dunnit? That implies an unconscious use of PEDMAS etc., whether or not you are explicitly aware of it. You could expand on PEDMAS /BODMAS by putting a big 'F' in front of them, meaning Functions.
Familiarity breeds contempt.

 

[micromass]

Let's write ##3x^2 + 5x + 7 = 0## without PEDMAS:

[tex] (((3\cdot x)\cdot x) + (5\cdot x)) + 7 = 9 [/tex]

Don't know about you, but I prefer to have this whole PEDMA convention...

 

[fresh_42]

So, ##\log_2 32 = 5 \text{ trees ?}##

Well almost. But at least in terms of quality.
I found ##\ln V_t = 1.34 + 0.394 \ln G_0 + 0.346 \ln t +0.00275 \, S_h t^{-1}##

"Such equations have not been used much in mixed forests, but Mendoza and Gumpal (1987) predicted yield of dipterocarps in the Philippines with an empirical function of initial basal area, site quality and time since logging, where ##V_t## is timber yield (##m^3 ha^{-1} , 15+ cm \; dbh##), ##t## years after logging (##t>0##), ##G_0## is residual basal area (##m^2 ha^{-1}##) of dipterocarps (##15+ cm \; dbh##) after logging, and ##S_h## is site quality (##m##) estimated as the average total height of residual dipterocarp trees (##50–80 cm## diameter)."

[Modelling forest growth and yield : applications to mixed tropical forests; Jerome K. Vanclay; Southern Cross University; 1994]

 

[PeroK]

3p+2q makes sense to you, dunnit?

Not really. Yes, I know what you mean, but it's not the way I or any maths text would write it. It would be:

##3p + 2q##

The spaces are important and indicate that I have two terms added together. I wouldn't go so far as to say that 3p+2q is wrong, but it's not something I would ever write.

In general, I would tend to agree with the ISO standard on mathematical symbols:

http://www.ise.ncsu.edu/jwilson/files/mathsigns.pdf

This, I believe, is closer to what most professional mathematicians naurally would adhere to. There is no mention of PEMDAS or order of operations there.

 

[PeroK]

Let's write ##3x^2 + 5x + 7 = 0## without PEDMAS:

[tex] (((3\cdot x)\cdot x) + (5\cdot x)) + 7 = 9 [/tex]

Don't know about you, but I prefer to have this whole PEDMA convention...

I refer you also to the ISO standard, which makes the quadratic expression quite clear without the need for PEMDAS.

There is no more need to ignore spaces in a line of mathematics than a line of text.

 

[micromass]

Not really. Yes, I know what you mean, but it's not the way I or any maths text would write it. It would be:

##3p + 2q##

The spaces are important and indicate that I have two terms added together. I wouldn't go so far as to say that 3p+2q is wrong, but it's not something I would ever write.

In general, I would tend to agree with the ISO standard on mathematical symbols:

http://www.ise.ncsu.edu/jwilson/files/mathsigns.pdf

This, I believe, is closer to what most professional mathematicians naurally would adhere to. There is no mention of PEMDAS or order of operations there.

?? You're proposing to replace PEMDA's by "spaces"?? Come on...

 

[micromass]

I refer you also to the ISO standard, which makes the quadratic expression quite clear without the need for PEMDAS.

There is no more need to ignore spaces in a line of mathematics than a line of text.

I personally don't know any professional mathematician who has even heard of this particular ISO standard, sorry. All of them has heard of PEMDA's though...

 

[micromass]

Seriously, I have read many books on sound mathematical writing. None of them says to use "spaces" instead of PEMDA's. That most professional mathematicians prefer "spaces" is just wrong.

 

[PeroK]

I personally don't know any professional mathematician who has even heard of the ISO standard, sorry.

I never said they had. I said that if you look at maths publications they naturally follow the standard. A case of the standard describing how things are done, rather than the standard coming first.

 

[PeroK]

Seriously, I have read many books on sound mathematical writing. None of them says to use "spaces" instead of PEMDA's. That most professional mathematicians prefer "spaces" is just wrong.

Then why did you put spaces in your quadratic expression?

 

[micromass]

I never said they had. I said that if you look at maths publications they naturally follow the standard. A case of the standard describing how things are done, rather than the standard coming first.

I have read hundreds of math publications and I have never seen what you describe.

 

[micromass]

Then why did you put spaces in your quadratic expression?

I didn't. LaTeX did it.

 

[PeroK]

I didn't. LaTeX did it.

I wonder why?

 

[micromass]

I wonder why?

Name me one professional mathematician or article that thinks 2p+3q is invalid.

 

[PeroK]

I wonder why?

Or, should I say "Iwonderwhy?"

 

[PeroK]

Name me one professional mathematician or article that thinks 2p+3q is invalid.

As I said, I wouldn't say it's actually wrong, but I've never seen a textbook that doesn't have spaces between terms. Perhaps there are some, but it's always the way LATEX renders it on here. All the books I have would have:

##ax^2 + bx + c##

I've never seen ax^2+bx+c.

 

[micromass]

As I said, I wouldn't say it's actually wrong, but I've never seen a textbook that doesn't have spaces between terms. Perhaps there are some, but it's always the way LATEX renders it on here. All the books I have would have:

##ax^2 + bx + c##

I've never seen ax^2+bx+c.

You clearly never read older textbooks that didn't use LaTeX then.

Sure, nowadays LaTeX using spacing accurately because it increases readability. There is no actual formal rule that acknowledges spacing though...

 

[micromass]

Well, in my newest math paper, I'm going to write something like

[tex]2~\cdot ~x\! + \! y[/tex]

to mean ##2(x+y)##. I'm pretty sure the reviewer will look at it and say "hey, he used spaces, so of course it's correct".

 

[PeroK]

You clearly never read older textbooks that didn't use LaTeX then.

Sure, nowadays LaTeX using spacing accurately because it increases readability. There is no actual formal rule that acknowledges spacing though...

I never said there was. I said that some of us naturally use spacing the way we use it when writing - to separate terms.

If what I would like to be rules was the rules it wouldn't be my pet peeve would it? It's only my pet peeve because I know there's PEMDAS out there and I know we're all supposed to have memorised the whole damn thing and we're all supposed to think that:

(a) 6+3-1/3+1*0-4^3+1x2

Makes perfect sense. And the question of whether this mess equals 951 or 67 is of some mathematical consequence. And that there is no rule (which I think there should be) that says that (a) is a mess and not maths at all. I know that some people think that evaluating (a) is the pinnacle of arithmetic achievement. And, if I made the rules, then yes I would declare (a) to be mathematical nonsense. The fact that it is not deemed nonsense is my peeve.

 

[PeroK]

Well, in my newest math paper, I'm going to write something like

[tex]2~\cdot ~x\! + \! y[/tex]

to mean ##2(x+y)##. I'm pretty sure the reviewer will look at it and say "hey, he used spaces, so of course it's correct".

Sorry, micromass, that's deliberately misunderstanding!

 

[micromass]

I never said there was. I said that some of us naturally use spacing the way we use it when writing - to separate terms.

If what I would like to be rules was the rules it wouldn't be my pet peeve would it? It's only my pet peeve because I know there's PEMDAS out there and I know we're all supposed to have memorised the whole damn thing and we're all supposed to think that:

(a) 6+3-1/3+1*0-4^3+1x2

Makes perfect sense. And the question of whether this mess equals 951 or 67 is of some mathematical consequence. And that there is no rule (which I think there should be) that says that (a) is a mess and not maths at all. I know that some people think that evaluating (a) is the pinnacle of arithmetic achievement. And, if I made the rules, then yes I would declare (a) to be mathematical nonsense. The fact that it is not deemed nonsense is my peeve.

So you would build math software that declares (a) to be an erroneous expression?

 

[Mark44]

Let's write ##3x^2 + 5x + 7 = 0## without PEDMAS:

[tex] (((3\cdot x)\cdot x) + (5\cdot x)) + 7 = 9 [/tex]

Don't know about you, but I prefer to have this whole PEDMA convention...

And if we view the above in the context of programming languages (such as C, C++, C#, Java, etc.), we should do this:
$$((((3\cdot x)\cdot x) + (5\cdot x)) + 7) = 9$$
The assignment operator, =, has a precedence lower than almost all of the other operators. If we ignore the precedence rules, sort of akin to ignoring PEDMAS, we would need to use another pair of parentheses around the entire expression on the left.

I'm being a bit facetious, though, as the above wouldn't qualify as an assignment expression ...