# 0.7 Presentation layout elements (mrow, mfrac, msqrt, mroot)

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Lay out elements are responsible for two dimensional structure, arrangement and final appearnce by the rendering system.

Layout elements control two dimensional layout of characters, symbols and composed expressions. There are three groups of elements that determine the two dimensional lay out of the mathematical content and affects its maangement.

## Layout element groups

• Basic layout elements
• Scripting elements
• Table elements

Basic layout elements comprises of 10 elements. The names and their basic role in rendering layout are listed here :

## Basic layout elements

• “mrow” : makes horizontal groups of sub-expressions for variety of purposes
• “mfrac : renders elements in P/Q form
• “msqrt” : renders a square root
• “mroot” : renders a radical with an index
• “mstyle : set environment attributes for the enclosed elements
• “merror : enclose a syntax error message from a preprocessor
• “mpadded” : manages space around content
• “mphantom” : makes content invisible, while maintaining structure
• “mfenced” : Segregates terms with separators and surround its content with a pair of fences
• “menclose” : enclose content with a stretching symbol

## ”mrow” layout element

The “mrow” element is a horizontal sub-grouping facility. Grouping of sub expression is an important requirement for variety of reasons. Primarily, this element determines the relationship between an “operator” and “operand”. When there is single character “operator” and “operand” relationship, then grouping is not an issue. However, when there more than one “operand” in an expression, then grouping is required.

Grouping of elements is also important where elements require certain numbers of argument. In such situation, it is possible that there are more child elements than the arguments required. Consider the example here, where child elements are grouped to meet the requirement of “mfrac” syntax for two arguments.

## "mfrac" layout element

<m:math display="block"> <m:mfrac> <m:mrow> <m:mi>x</m:mi> <m:mo>+</m:mo> <m:mn>y</m:mn> </m:mrow> <m:mn>z</m:mn> </m:mfrac> </m:math>

Save the file after editing as “test.xml”. The display looks like :

$\frac{x+y}{z}$

In the example above, “mrow” element is used to group the sub-expression “x + y” to be treated as numerator in “mfrac” implementation.

We have also seen earlier that “mrow” plays important role in determining the form of an operator. The form of an operator as “prefix” or “infix” or “postfix” is determined by the position of an operator in the group of sub expression defined by “mrow” element.

Grouping of elements, terms and sub-expressions (in yet another sub-expression) is a common requirement for meaningful mathematical expression. As such, MathML platform implements an inferred mechanism, whereby certain elements infer that the child elements are grouped with “mrow” in an implicit manner. This means that we may save on writing a pair of “mrow” tags in such situation.

Is there any normative that regulates the use of silver nanoparticles?
what king of growth are you checking .?
Renato
What fields keep nano created devices from performing or assimulating ? Magnetic fields ? Are do they assimilate ?
why we need to study biomolecules, molecular biology in nanotechnology?
?
Kyle
yes I'm doing my masters in nanotechnology, we are being studying all these domains as well..
why?
what school?
Kyle
biomolecules are e building blocks of every organics and inorganic materials.
Joe
anyone know any internet site where one can find nanotechnology papers?
research.net
kanaga
sciencedirect big data base
Ernesto
Introduction about quantum dots in nanotechnology
what does nano mean?
nano basically means 10^(-9). nanometer is a unit to measure length.
Bharti
do you think it's worthwhile in the long term to study the effects and possibilities of nanotechnology on viral treatment?
absolutely yes
Daniel
how to know photocatalytic properties of tio2 nanoparticles...what to do now
it is a goid question and i want to know the answer as well
Maciej
Abigail
for teaching engĺish at school how nano technology help us
Anassong
Do somebody tell me a best nano engineering book for beginners?
there is no specific books for beginners but there is book called principle of nanotechnology
NANO
what is fullerene does it is used to make bukky balls
are you nano engineer ?
s.
fullerene is a bucky ball aka Carbon 60 molecule. It was name by the architect Fuller. He design the geodesic dome. it resembles a soccer ball.
Tarell
what is the actual application of fullerenes nowadays?
Damian
That is a great question Damian. best way to answer that question is to Google it. there are hundreds of applications for buck minister fullerenes, from medical to aerospace. you can also find plenty of research papers that will give you great detail on the potential applications of fullerenes.
Tarell
what is the Synthesis, properties,and applications of carbon nano chemistry
Mostly, they use nano carbon for electronics and for materials to be strengthened.
Virgil
is Bucky paper clear?
CYNTHIA
carbon nanotubes has various application in fuel cells membrane, current research on cancer drug,and in electronics MEMS and NEMS etc
NANO
so some one know about replacing silicon atom with phosphorous in semiconductors device?
Yeah, it is a pain to say the least. You basically have to heat the substarte up to around 1000 degrees celcius then pass phosphene gas over top of it, which is explosive and toxic by the way, under very low pressure.
Harper
Do you know which machine is used to that process?
s.
how to fabricate graphene ink ?
for screen printed electrodes ?
SUYASH
What is lattice structure?
of graphene you mean?
Ebrahim
or in general
Ebrahim
in general
s.
Graphene has a hexagonal structure
tahir
On having this app for quite a bit time, Haven't realised there's a chat room in it.
Cied
what is biological synthesis of nanoparticles
how did you get the value of 2000N.What calculations are needed to arrive at it
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