7377	2012-03-30 09:48:47	Stephen Farthing	Equations.......
Message	Date	From	Subject
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. xy+a/b is equal to (xy)+(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.......
> > 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? > (Vcc * R1) + (Veb * B * Rc) Vc = ----------------------------- (B * Rc) + R1 > > Also, where there are no units defined for a value of, for example, a > capacitor, what is the assumption. > In Fig. 2.16, the "0.1" is in uF, and that seems to prevail throughout that 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 kd5yyk
7387	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 Subtracti
7388	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 M0RCP
7389	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, VK6JT
7390	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