Division of Mathematical Expressions Between Braille Lines

[Mary Mosley]

In a physics book, a large expression

a .k ?3 kg -0.2(1 kg + 2 kg)/1 kg +2 kg +3 kg#9.81 ;m_/;s^2 .k #3.92 ;m_/;s^2

will clearly not fit on a single line. Starting with Priority #1, I divide at the equals, giving me:

a
.k ?3 kg -0.2(1 kg + 2 kg)/1 kg +2 kg +3 kg#9.81 ;m_/;s^2
.k #3.92 ;m_/;s^2

The first link containing the fraction will still not fit. Thus I move to Priority #2, operators. This expression has an implied operator, as 9.81 is multiplied by the preceding fraction, and even if I have to move to Priority #3, would have to break at all higher priorities. As there are no examples of this in the 2019 revised version of the 2017 introduction to braille mathematics. I am assuming there would be no numeric indicator on the 9.81, as if the multiplication operator was there, and to not make it seem that 9.81 was starting a new expression (though the indentation would also preclude this), thus giving me:

a
.k ?3 kg -0.2(1 kg + 2 kg)/1 kg +2 kg +3 kg#
9.81 ;m_/;s^2
.k #3.92 ;m_/;s^2

Still, the fraction does not fit on a single line, so I move to Priority #3, Fraction lines. Breaking the first link at the fraction line gives me:

a
.k ?3 kg -0.2(1 kg + 2 kg)
/1 kg +2 kg +3 kg#
9.81 ;m_/;s^2
.k #3.92 ;m_/;s^2

Breaking at the fraction line, as stated before, means all Priority #1 and #2 outside of the fraction are required to break. My question is, am I applying 14.11 and 14.12 et al. correctly in the division of this expression, and am I correct in omitting the numeric indicator.

[Lindy Walton]

Hi Veeah.

The division of expression guidelines are hard to understand, and frankly are not very clear in the code because of the wide variation in issues we face with long expressions.
Over the years, we all got a little carried away trying to make sense of the priority list outlined in the code book.

In retrospect, the statement in Lesson 14 that says "If an expression must be divided at a site lower on the priority list, a new line is required at each sign which occurs higher on the list" is simply not practical. You'll be happy to hear that this topic will be easier to comprehend in the updated lesson material and code book, due out some time in 2022. In the meantime...

Honestly, the concept is simple and if we step back a bit, usually we can come up with a clear transcription.

In a long linked expression, the first thing to keep in mind is to begin each link on a new line. There are two links in your example. A new line begins with each of those links, beginning with the equals sign. When the anchor is so small (in this case, "a"), it may seem strange to leave it all alone on a line by itself, but by starting each link on a new line, the structure of the equation is not lost.

The issue now is what to do with the long fraction. Yes, divide before the fraction line, to keep the numerator distinct from the denominator. A numeric indicator is not needed for the "1" in the denominator because it is not preceded by a space.

Now what to do with the factor "9.81 m/s^2"? Since no operation sign is present, you don't need to begin a new line. It's okay if you do, for clarity, but it's not required. If you do begin a new line with "9.81 m/s^2" then you need a numeric indicator before the 9 because it is the first symbol on the line. On the other hand, if you keep "9.81 m/s^2" unspaced from the closing fraction indicator on the previous line, the numeric indicator is not needed.

One correction needed: Delete the space between the plus symbol and "2" in the numerator.

I love your questions. Thank you for sharing this with everyone on the forum.

Lindy

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