**EMRFD Message Archive 7377**

MessageDateFromSubject7377 2012-03-30 09:48:47 Stephen Farthing Equations....... Hi Guys,

I am working my way through EMRFD and I am getting a bit confused with the

way the equations are expressed. I am trying to use Equation 2.9 but I am

not sure how to evaluate the terms because of the lack of brackets (I think

you call them parenthesis in the USA). Can someone give me a hint as to how

you do things over there in the land where the buffalo roam?

Also, where there are no units defined for a value of, for example, a

capacitor, what is the assumption.

It is a long time since I have had to exercise the mathematical side of my

brain so please keep things simple.

73s Steve G0XAR

Wisdom demands a new orientation of science and technology towards the

organic, the gentle, the non-violent, the elegant and beautiful. E. F.

Schumacher

[Non-text portions of this message have been removed]7378 2012-03-30 10:29:52 Lasse Re: Equations....... Stephen,

I do not have the book handy right now, so cannot comment on the

equations in question, but

generally, if nothing else is said, C is stated in Farads and L in

Henry's and frequency in Hz

If no brackets, always multiply and divide prior to addition/subtraction

i.e. x*y+a/b is equal to (x*y)+(a/b) and (x+y)*(a+b) needs brackets to

calculate correctly

/Lasse SM5GLC

Stephen Farthing skrev 2012-03-30 18:48:

> Hi Guys,

>

> I am working my way through EMRFD and I am getting a bit confused with the

> way the equations are expressed. I am trying to use Equation 2.9 but I am

> not sure how to evaluate the terms because of the lack of brackets (I think

> you call them parenthesis in the USA). Can someone give me a hint as to how

> you do things over there in the land where the buffalo roam?

>

> Also, where there are no units defined for a value of, for example, a

> capacitor, what is the assumption.

>

> It is a long time since I have had to exercise the mathematical side of my

> brain so please keep things simple.

>

> 73s Steve G0XAR

>

> Wisdom demands a new orientation of science and technology towards the

> organic, the gentle, the non-violent, the elegant and beautiful. E. F.

> Schumacher

>

>

> [Non-text portions of this message have been removed]

>

>

>

> ------------------------------------

>

> Yahoo! Groups Links

>

>

>

>

>7379 2012-03-30 11:02:12 Chris Trask Re: Equations....... >think

> I am working my way through EMRFD and I am getting a bit confused with the

> way the equations are expressed. I am trying to use Equation 2.9 but I am

> not sure how to evaluate the terms because of the lack of brackets (I

> you call them parenthesis in the USA). Can someone give me a hint as tohow

> you do things over there in the land where the buffalo roam?(Vcc * R1) + (Veb * B * Rc)

>

Vc = -----------------------------

(B * Rc) + R1

>In Fig. 2.16, the "0.1" is in uF, and that seems to prevail throughout that

> Also, where there are no units defined for a value of, for example, a

> capacitor, what is the assumption.

>

chapter.

Chris

,----------------------. High Performance Mixers and

/ What's all this \ Amplifiers for RF Communications

/ extinct stuff, anyhow? /

\ _______,--------------' Chris Trask / N7ZWY

_7380 2012-03-30 12:29:47 Graham / KE9H Re: Equations....... Stephen:

What is 2 + 3 x 4 = ?

If your answer is 20, then you need to go back to school

(or change to a better school.)

The correct answer is 14.

If there are no brackets or parenthesis, then the operators

in the equation should be evaluated according to the

"order of operations" or "operator precedence."

http://en.wikipedia.org/wiki/Operator_precedence

This is an important mathematical concept, and is

universal in mathematics, but quite frankly, poorly

taught in school, at least here in the U.S.

Many people really don't understand the importance

of operator precedence until they have done a little

programming.

--- Graham / KE9H

==

7381 2012-03-30 12:41:44 Stephen Farthing Re: Equations....... Hi Graham,

Thanks, when I was at school and university we parenthesised everything to

avoid any ambiguity....I carried this habit with me when I programmed for a

living.

73s Steve

--

Wisdom demands a new orientation of science and technology towards the

organic, the gentle, the non-violent, the elegant and beautiful. E. F.

Schumacher

[Non-text portions of this message have been removed]7383 2012-03-30 17:28:55 Julio Jimenez Re: Equations....... Stephen,

I agree with you. Even though an equation might be mathematically correct without brackets or parentheses, it just looks better and lends itself to less confusion when it's properly grouped. I believe your question was completely valid and it would be a definite improvement in future EMRFD editions.

Understanding the order of operations is important, but I don't think the school you attend has much to do with it. I went to high school in Dominican Republic and university in North Carolina and we always grouped our equations where needed. Actually, the only time I remember not doing it was during introductory classes explaining the order of operations.

73

Julio

KK4EQP

Sent from my iPhone

>[Non-text portions of this message have been removed]

7384 2012-03-30 17:29:02 Bill Wright Re: Equations....... All

I was in the school house many many years ago. We learned arithmetic order using the

sage of "My Dear Aunt Sally" That is multiply/divide/add/subtract inside outside the parens/brackets.

We had one for Trig functions too. "Oscar Had A Heap Of Apples" You can figure that out I think

3 Bill

kd5yyk

________________________________

7385 2012-03-30 17:40:55 William Carver Re: Equations....... If there is EVER any question, use parentheses.

If you want someone to INSTANTLY see what's being done, use parentheses.

Even (especially) if you're a programmer.

W7AAZ

On Fri, 2012-03-30 at 14:29 -0500, Graham / KE9H wrote:

>

> Stephen:

>

> What is 2 + 3 x 4 = ?

>

> If your answer is 20, then you need to go back to school

> (or change to a better school.)

>

> The correct answer is 14.

>

> If there are no brackets or parenthesis, then the operators

> in the equation should be evaluated according to the

> "order of operations" or "operator precedence."

>

> http://en.wikipedia.org/wiki/Operator_precedence

>

> This is an important mathematical concept, and is

> universal in mathematics, but quite frankly, poorly

> taught in school, at least here in the U.S.

>

> Many people really don't understand the importance

> of operator precedence until they have done a little

> programming.

>

> --- Graham / KE9H

>

> ==

>

>7386 2012-03-31 00:20:03 John Kolb Re: Equations....... Please Favor My Dear Aunt Sally. Parens Fractions Multiply Divide Add Subtract.

John

At 04:53 PM 3/30/2012, you wrote:

All

I was in the school house many many years ago.Â We learned arithmetic order using the

sage of "My Dear Aunt Sally"Â That is multiply/divide/add/subtract inside outside the parens/brackets.

We had one for Trig functions too. "Oscar Had A Heap Of Apples"Â You can figure that out I think

3 Bill

kd5yyk7387 2012-03-31 04:18:27 d29602960 Re: Equations....... Hi Steve and the group,

When I was at school they told us to remember BODMAS!

B = Brackets first

O = Orders (ie Powers and Square Roots, etc.)

DM = Division and Multiplication (left-to-right)

AS = Addition and Subtracti7388 2012-03-31 13:41:01 Richard Peterson Re: Equations....... In the UK all secondary school pupils are taught the mnemonic

BODMAS (or alternatively BIDMAS) to help them remember

the order in which operations should be carried out when evaluating

an expression:

Brackets

Operations (or Indices)

Divides

Multiplies

Adds

Subtracts

Whether they pay any attention is another matter.

73 Rick M0RCP7389 2012-03-31 17:21:06 Hector Pascal Re: Equations....... In my experience of teaching Uni EE students, remarkably few have that

long term a memory! But luckily most are saved by the constraints

imposed by their calculators!

David, VK6JT7390 2012-03-31 18:27:35 Ashhar Farhan Re: Equations....... Here is sal on the topic ...

http://www.khanacademy.org/math/arithmetic/order-of-operations/v/introduction-to-order-of-operations

Watch the next video as well.

- farhan

On 4/1/12, Hector Pascal <hector.pascal@gmail.com> wrote:

> In my experience of teaching Uni EE students, remarkably few have that

> long term a memory! But luckily most are saved by the constraints

> imposed by their calculators!

>

> David, VK6JT

>

--

Sent from my mobile device