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## Re: Alt text for equations

On Wed, 2 Jun 2010 06:37:53 +0000 (UTC), Neredbojias wrote:

The problem is, that if you read that aloud, the hearer is still

likely to think that 7 is multiplied by 2, not that n-7 is multiplied

by 2. You can do it with pauses in the voice, but I'm not sure we

can count on text-to-speech programs doing that.

There may not be a solution to this problem -- at least, I haven't

seen a credible one so far. But the discussion has been good: it

prompted me to change some of the less complicated GIFs to text. I

just wish I could do a better job on the alt texts of the remaining

ones, but that may not be possible.

--

Stan Brown, Oak Road Systems, Tompkins County, New York, USA

http://OakRoadSystems.com /

HTML 4.01 spec: http://www.w3.org/TR/html401 /

validator: http://validator.w3.org /

CSS 2.1 spec: http://www.w3.org/TR/CSS21 /

validator: http://jigsaw.w3.org/css-validator /

Why We Won't Help You:

http://diveintomark.org/archives/2003/05/05/why_we_wont_help_you

## Re: Alt text for equations

x equals minus b plus or minus the square root of b squared minus four a

c all over two a.

No, I'm quite sure it hasn't progressed the discussion in the slightest.

I just wanted to prove that I could still remember it, after reciting it

in class so often, fifty years ago.

I'll fetch my coat.

--

Molly Mockford

Nature loves variety. Unfortunately, society hates it. (Milton Diamond Ph.D.)

(My Reply-To address *is* valid, though may not remain so for ever.)

## Re: Alt text for equations

In comp.infosystems.www.authoring.html message <CLckvz1TZlBMFwyI@molly.m

*ockford>, Wed, 2 Jun 2010 14:02:11, Molly Mockford <nospamnobody@mollymo*

*ckford.me.uk> posted:*

But can you remember being taught how to decide whether to use the plus

case or the minus case?

--

(c) John Stockton, nr London, UK. ?@merlyn.demon.co.uk Turnpike v6.05.

Web <URL:http://www.merlyn.demon.co.uk/ - w. FAQish topics, links, acronyms

PAS EXE etc : <URL:http://www.merlyn.demon.co.uk/programs/ - see 00index.htm

Dates - miscdate.htm estrdate.htm js-dates.htm pas-time.htm critdate.htm etc.

## Re: Alt text for equations

At 18:17:35 on Thu, 3 Jun 2010, Dr J R Stockton

It isn't a matter of choosing. The solution for x in a quadratic

equation is "+n or -n", and both cases are valid, because both of them

are solutions to "root n-squared"; in other words, either of them, when

squared, becomes n-squared. No decision between a positive or a

negative solution can possibly be warranted.

--

Molly Mockford

Nature loves variety. Unfortunately, society hates it. (Milton Diamond Ph.D.)

(My Reply-To address *is* valid, though may not remain so for ever.)

## Re: Alt text for equations

It depends on why you are solving the equation. Suppose you are solving

for the intersection of a line and a sphere. You make a quadratic

equation and solve it and the two roots tell you how far to go along the

line in order to touch the sphere. Of course if a line intersects a sphere

at all it usually does so in two places and these correspond to the two

roots.

Anyway, you might want the nearest one-- where you go into the sphere

rather than where you leave it on the other side (you probably want this

if you are writing a raytracer for example). That ends up being either

the +n or the -n solution, so you figure out which one and use that.

## Re: Alt text for equations

Ah, I suspect this is applied maths, whereas what I got taught for

O-level was pure maths. We were never given any

***reasons***for doing it;

doing it was supposed to be sufficient in itself.

This is why I gave up maths when we go to trig (let alone calculus);

nobody ever told me that sines, cosines and tangents were used for

interesting and practical stuff like oceanic navigation. No, the only

practical application they ever suggested was how long a ladder one

needed to reach a particular window. Even at that tender age, I had

never seen a man sit down with pencil and paper to solve that problem!

--

Molly Mockford

Nature loves variety. Unfortunately, society hates it. (Milton Diamond Ph.D.)

(My Reply-To address *is* valid, though may not remain so for ever.)

## Re: Alt text for equations

In Australia, it is compulsory for even window cleaners to have

matriculated in Applied maths and on the job to have waterproof

slide rules, notepads, tape measures and protractors on their

persons as they climb. Here we often see such with pencil and

paper as they perch on ladders, and indeed, tragically, we see

quite a few fall off as they obviously make minor mistakes in

their integrations...

--

dorayme

## Re: Alt text for equations

...and if only they had paid a bit more attention in their maths

classes, they would not have fallen with such immense speed, impetus and

acceleration as to have missed hitting the ground (Adams, D.) and

escaped the earth's gravitational field and spent the rest of their

brief Australian window-cleaner lives having their orbits described in

terms of cotangents and other abstruse bollocks. (Sorry 'bout that

bathos; no matter how glorious, every firework has to come down to

earth at some point.)

--

Molly Mockford

Nature loves variety. Unfortunately, society hates it. (Milton Diamond Ph.D.)

(My Reply-To address *is* valid, though may not remain so for ever.)

## Re: Alt text for equations

In comp.infosystems.www.authoring.html message <HEPVcLRRSDCMFwqG@molly.m

*ockford>, Fri, 4 Jun 2010 00:02:41, Molly Mockford <nospamnobody@mollymo*

*ckford.me.uk> posted:*

Disregard the obvious care where only one solution can be physically

valid (since that has already been discussed).

Algebraically, the "+" and "-" expressions are equally good.

But, numerically, consider the case where a is approximately equal to

the square root of b squared minus four a c. If the square root is

taken with the opposite sign to that of the value of a, then you will be

taking the difference of similar quantities, and your rounding errors

will be a much larger proportion of the result than if you had combined

the quantities.

So give the square root the same sign as the value of a, getting the

bigger root R, and from that calculate the smaller root r using the fact

that the product of the two algebraic solutions given by the expression

that you described simplifies to c divided by a.

Try it for (x-1e-3)*(x-1e+3) = 0 expanded to

ax^2 + bx + c with a = 1, b = -1000.0001, c = 1,

firstly using exact arithmetic and secondly using a slide rule or

4-figure log tables.

In JavaScript:

R directly : 1000

r directly : 0.0009999999999763531

r = c/(a*R) : 0.001

and there arithmetic is good to 53 bits.

--

(c) John Stockton, near London. *@merlyn.demon.co.uk/?.?.Stockton@physics.org

Web <URL:http://www.merlyn.demon.co.uk/ - FAQish topics, acronyms, & links.

Correct <= 4-line sig. separator as above, a line precisely "-- " (RFC5536/7)

Do not Mail News to me. Before a reply, quote with ">" or "> " (RFC5536/7)

## Re: Alt text for equations

True, maybe, but she would be dead wrong.

(n-7)*2 = The product of n minus 7 times 2.

n-7*2 = n minus 7 times 2 or n minus the product of 7 times 2.

Notice in the last definition the phrase "the product of" is completely

superfluous. That's why I say it

***indicates***summation even though it

means multiplication. Another can of worms here, but actually the word

"of" is the keyword.

Anyway, moving on, another way to voice the first line is "n minus 7

sum times 2", as I said before. Do you see the similarity with the 1st

definition, and, personally, I think it's less ambiguous-seeming.

However, neither choice is really ambiguous at all but may naturally

cause confusion for those not knowing the language.

By the way, "sum" means addition AND subtraction. "Product of" means

multiplication AND division. The halves of each pair are really the

same thing.

The best thing is to do it correctly and if some people misinterpret

what it means, so what else is new?

--

Neredbojias

http://www.neredbojias.org /

http://www.neredbojias.net /

## Re: Alt text for equations

Yes, as described by the exact phrasing regardless of word sequence.

Note that "The product of 2 times the difference of n minus 7" === "the

product of n minus seven times 2" which is more efficient wording.

Likewise, "The difference of n minus the product of 7 times 2" === "n

minus 7 times 2". This is because of the

***mathematical***hierarchy

which even third-graders should know.

--

Neredbojias

http://www.neredbojias.org /

http://www.neredbojias.net /

## Re: Alt text for equations

In comp.infosystems.www.authoring.html message <MPG.26700a8f1b4f544898c3

*08@news.individual.net>, Wed, 2 Jun 2010 07:29:08, Stan Brown*

^^^^^^^^^^^^^^

<http://en.wikipedia.org/wiki/Stan_Brown

There is no problem if the calculation is written and spoken in RPN.

--

(c) John Stockton, nr London UK. ?@merlyn.demon.co.uk Turnpike v6.05 MIME.

Web <URL:http://www.merlyn.demon.co.uk/ - FAQish topics, acronyms, & links.

Proper <= 4-line sig. separator as above, a line exactly "-- " (RFCs 5536/7)

Do not Mail News to me. Before a reply, quote with ">" or "> " (RFCs 5536/7)

## Re: Alt text for equations

On Thu, 3 Jun 2010 18:12:54 +0100, Dr J R Stockton wrote:

Wikipedia gets it wrong, again. I'm not retired, and I've never

played professional basketball.

--

Stan Brown, Oak Road Systems, Tompkins County, New York, USA

http://OakRoadSystems.com /

HTML 4.01 spec: http://www.w3.org/TR/html401 /

validator: http://validator.w3.org /

CSS 2.1 spec: http://www.w3.org/TR/CSS21 /

validator: http://jigsaw.w3.org/css-validator /

Why We Won't Help You:

http://diveintomark.org/archives/2003/05/05/why_we_wont_help_you

## Re: Alt text for equations

Neredbojias wrote:

[Full quote intended]

Yes, to place "sum" after the operand and before the operator it was/is your

invention.

Hear, hear.

There is no disagreement

***there***. However, when using this phrasing

unambiguousness is (also) not guaranteed with more complex equations.

PointedEars

--

Prototype.js was written by people who don't know javascript for people

who don't know javascript. People who don't know javascript are not

the best source of advice on designing systems that use javascript.

## Re: Alt text for equations

Well modesty prevented me from taking credit for it but since you've

pandered to my vanity...

I don't know... True, it may very well be impossible to understand,

but would the accuracy of the wording be compromised by complexity?

--

Neredbojias

http://www.neredbojias.org /

http://www.neredbojias.net /

## Re: Alt text for equations

On Wed, 2 Jun 2010 13:22:52 +0000 (UTC), Neredbojias wrote:

That's been my problem with every one of your formulations that I've

seen so far. The job of an alt text for an equation is to make the

equation comprehensible for someone who can't see it. Your

formulations of (n-7)*2 don't do that for me, even though the

expressions you're using as examples are considerably simpler than

the equations I have to present.

I do wish someone would answer the question I asked: what do (most)

text-to-speech readers do with parentheses and brackets? If they

read them aloud, that would simplify my job considerably.

--

Stan Brown, Oak Road Systems, Tompkins County, New York, USA

http://OakRoadSystems.com /

HTML 4.01 spec: http://www.w3.org/TR/html401 /

validator: http://validator.w3.org /

CSS 2.1 spec: http://www.w3.org/TR/CSS21 /

validator: http://jigsaw.w3.org/css-validator /

Why We Won't Help You:

http://diveintomark.org/archives/2003/05/05/why_we_wont_help_you

## Re: Alt text for equations

I don't think you're going to get an answer to that question, at

least not here. Other than searching for a group dedicate to screen

readers or asking in the ciw.browsers.* groups, you could always

contact your college/university accessibility office and see if they

can put you in touch with people who use such things?

I'd be interested to know what you find out, as I have plenty of

pages with graphics of equations on them, and I don't really know

what to do either!

## Re: Alt text for equations

In comp.infosystems.www.authoring.html message <6PVq+pG2X9BMFw1q@molly.m

*ockford>, Thu, 3 Jun 2010 17:19:02, Molly Mockford <nospamnobody@mollymo*

*ckford.me.uk> posted:*

The OP is an alien. He may do better to ask via http://www.afb.org /.

--

(c) John Stockton, nr London UK. ?@merlyn.demon.co.uk Turnpike v6.05 MIME.

Web <URL:http://www.merlyn.demon.co.uk/ - FAQish topics, acronyms, & links.

Proper <= 4-line sig. separator as above, a line exactly "-- " (RFCs 5536/7)

Do not Mail News to me. Before a reply, quote with ">" or "> " (RFCs 5536/7)

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