Beginner: Integer FFT and Fixed Point FFT

bhooshaniyer wrote:

(snip)

>>of the product depends on the sum of the digits after the binary point
>>of the numbers being multiplied, so only the sum needs to be known.

>>For addition and subtraction the binary points must agree, but the 
>>hardware doesn't care which position it is, as long as they are both the

> Mmmm...I think you are right but am not sure if I understand what you said
> well enough to be sure...If you dont mind you could expand a bit more with
> may be an example...I guess it would be useful for many of us...


How about a decimal example.

If I multiply fixed decimal numbers,  0.02 * 900, 00.2*90.0 or
002 * 9.00, the product is 18.00 in all three cases.

The hardware sees 002 and 900 and gives 001800, and I know where
the decimal point goes, two places from the right in three cases.

-- glen

Jerry Avins wrote:

> Richard Owlett wrote:
> 
>   ...
> 
>> A register just holds a bit pattern.
>>
>> If you think binary it contains value (perhaps signed) from 0 to 2^N -1
>> If scaled there is a *fixed* divisor/multiplier of 2^M
>>
>> So fixed-point and integer appears to be a "distinction *without* a 
>> difference".
> 
> 
> Those bits might represent ASCII characters. Is that distinction also 
> without difference?


Implied universe of discourse was *computation*



> 
> The difference is what you do with the bits. When multiplying 
> fixed-point numbers, you use the integer multiplier then shift the 
> result and discard different bits than you would if they were integers. 
> When adding, two fixed-point numbers with the same scaling, you use the 
> integer adder and accept the result as is. If the scaling isn't the same 
> for both numbers, at least one of them must be adjusted by shifts.


I still think of "integer" and "scaled integer" as same beast.
with either you need to keep track of context.

They are intrinsically different than a "float".


> 
> Jerry

Richard Owlett wrote:
> Jerry Avins wrote:
> 
>> Richard Owlett wrote:
>>
>>   ...
>>
>>> A register just holds a bit pattern.
>>>
>>> If you think binary it contains value (perhaps signed) from 0 to 2^N -1
>>> If scaled there is a *fixed* divisor/multiplier of 2^M
>>>
>>> So fixed-point and integer appears to be a "distinction *without* a 
>>> difference".
>>
>>
>>
>> Those bits might represent ASCII characters. Is that distinction also 
>> without difference?
> 
> 
> 
> Implied universe of discourse was *computation*

The essential difference lies in how one interprets the bits. I merely 
turned up the contrast.

>> The difference is what you do with the bits. When multiplying 
>> fixed-point numbers, you use the integer multiplier then shift the 
>> result and discard different bits than you would if they were 
>> integers. When adding, two fixed-point numbers with the same scaling, 
>> you use the integer adder and accept the result as is. If the scaling 
>> isn't the same for both numbers, at least one of them must be adjusted 
>> by shifts.
> 
> 
> 
> I still think of "integer" and "scaled integer" as same beast.
> with either you need to keep track of context.
> 
> They are intrinsically different than a "float".

And from each other, when you have a multiplier (or divider) designed to 
handle both kinds. (I know of no processor that doesn't handle integer.) 
There are DSPs that have separate instructions for integer and simplex 
fixed-point multiplication, and HLLs that allow more general fixed-point 
math, as mentioned above in this thread. How much difference do you want 
in a distinction?

Jerry
-- 
Should any political party attempt to abolish Social Security,
unemployment insurance, and eliminate labor laws and farm programs,
you would not hear of that party again in our political history.
There is a tiny splinter group, of course, that believes that you can
do these things.  Among them are a few Texas oil millionaires, and an
occasional politician or businessman from other areas.  Their number
is negligible, and they are stupid.
                    - Pres. Dwight D. Eisenhower, November 8, 1954

Jerry--

>Should any political party attempt to abolish Social Security,
>unemployment insurance, and eliminate labor laws and farm programs,
>you would not hear of that party again in our political history.
>There is a tiny splinter group, of course, that believes that you can
>do these things.  Among them are a few Texas oil millionaires, and an
>occasional politician or businessman from other areas.  Their number
>is negligible, and they are stupid.
>                    - Pres. Dwight D. Eisenhower, November 8, 1954

Wow! Please dont be telling me that you did not make that one up?!
If thats not prophecy, tell me what is! Hair raising stuff.

ps:Is'nt that an irony that none of the democratic lord snooties seem to
know their Eisenhower/Presidential history? To have a quote like that and
to not use it...seems to me howard dean needs to go...along with the rest
of the current crop of democrats!

--Bhooshan



		
This message was sent using the Comp.DSP web interface on
www.DSPRelated.com

dunno why you are blaming the Democrats (perhaps for being spineless, that
would fit).  it's the Republicans who are so hypocritical and forgetful of
their own heritage.  Eisenhower and Lincoln and T Roosevelt must all be
spinning in their graves.

in article gJWdnSvjUL6JNAvfRVn-rA@giganews.com, bhooshaniyer at
bhooshaniyer@gmail.com wrote on 05/27/2005 00:59:

>> Should any political party attempt to abolish Social Security,
>> unemployment insurance, and eliminate labor laws and farm programs,
>> you would not hear of that party again in our political history.
>> There is a tiny splinter group, of course, that believes that you can
>> do these things.  Among them are a few Texas oil millionaires, and an
>> occasional politician or businessman from other areas.  Their number
>> is negligible, and they are stupid.
>> - Pres. Dwight D. Eisenhower, November 8, 1954
> 
> Wow! Please dont be telling me that you did not make that one up?!
> If thats not prophecy, tell me what is! Hair raising stuff.

Every gun that is made, every warship launched, every rocket fired,
signifies in the final sense a theft from those who hunger and are not fed,
those who are cold and are not clothed.

Controlled, universal disarmament is the imperative of our time. The demand
for it by the hundreds of millions whose chief concern is the long future of
themselves and their children will, I hope, become so universal and so
insistent that no man, no government anywhere, can withstand it.

Here in America we are descended in blood and in spirit from revolutionists
and rebels - men and women who dare to dissent from accepted doctrine. As
their heirs, may we never confuse honest dissent with disloyal subversion.

I hate war as only a soldier who has lived it can, only as one who has seen
its brutality, its futility, its stupidity.

I like to believe that people in the long run are going to do more to
promote peace than our governments. Indeed, I think that people want peace
so much that one of these days governments had better get out of the way and
let them have it. 

In the councils of government, we must guard against the acquisition of
unwarranted influence, whether sought or unsought, by the
military-industrial complex. The potential for the disastrous rise of
misplaced power exists and will persist.


-- 

r b-j                  rbj@audioimagination.com

"Imagination is more important than knowledge."

rbj--

>dunno why you are blaming the Democrats (perhaps for being spineless,
>that would fit)

Sorry for being cryptic there. Yes you are right.

I blame the dems for being so pussilanamous, so cowardly and so not sure
about their philosiphies. They are so scared about being branded anti-war,
hence anti-american. I despise them for having no courage to stand up and
state *anything* but would resort to whining and fillibuster elsewhere.
They present no alternative at this point nor will they present any time
in the future,unless someone rises from the ranks and speaks with a moral
authority so powerful and vision so clear that makes the regula american
feel that he is being represented in the true sense of the word. 

The future of the democrats is so bleak and so disastorous that somehow I
wish that America was not a two party system or still better I wish
America was ready for Coalition politics much like the Indian and Eurpoean
21st century. But for sure the democratic future is not in the kennedy's,
the boxers, the deans, the edwards, the clintons, (am thinking now and I
cant recollect the Democratic Presidential Candiate's name!)- that guy,
george soros, michael moore etc. THE man or woman is just not around the
corner. And thats bad news for Americans and the world.

I see nothing stopping Ruddi Guilliani.


ps:As someone said, Hillary seems to have more balls than the entire dem
boys put together, but unfortunately she is stuck at partial birth
abortions and gay marraige and her husbands UN nomination etc.

>it's the Republicans who are so hypocritical and forgetful of
>their own heritage.  Eisenhower and Lincoln and T Roosevelt must all be
>spinning in their graves.

That is true but they have men with vision, hunger and discipline.They lay
in waiting and have bid their time for the past two decades and now it is
their time in the sun. The Empire struck back.

>Every gun that is made, every warship launched, every rocket fired,
>signifies in the final sense a theft from those who hunger and are not
fed,
>those who are cold and are not clothed.
>
>Controlled, universal disarmament is the imperative of our time. The
demand
>for it by the hundreds of millions whose chief concern is the long future
of
>themselves and their children will, I hope, become so universal and so
>insistent that no man, no government anywhere, can withstand it.
>
>Here in America we are descended in blood and in spirit from
revolutionists
>and rebels - men and women who dare to dissent from accepted doctrine.
As
>their heirs, may we never confuse honest dissent with disloyal
subversion.
>
>I hate war as only a soldier who has lived it can, only as one who has
seen
>its brutality, its futility, its stupidity.
>
>I like to believe that people in the long run are going to do more to
>promote peace than our governments. Indeed, I think that people want
peace
>so much that one of these days governments had better get out of the way
and
>let them have it. 
>
>In the councils of government, we must guard against the acquisition of
>unwarranted influence, whether sought or unsought, by the
>military-industrial complex. The potential for the disastrous rise of
>misplaced power exists and will persist.

Wow! Cool Stuff, was this guy a soldier by any chance? Seems like it!
unfortunately my understanding of American Politics starts only from
Vietnam and upwards( triggered by the intrigue surrounding the Jason
Bourne series written by ...I forget his name.You know who!) so this
Eisenhower stuff is new to me.Very interesting!

--Bhooshan
		
This message was sent using the Comp.DSP web interface on
www.DSPRelated.com

robert bristow-johnson wrote:
> dunno why you are blaming the Democrats (perhaps for being spineless, that
> would fit).  it's the Republicans who are so hypocritical and forgetful of
> their own heritage.  Eisenhower and Lincoln and T Roosevelt must all be
> spinning in their graves.
> 
> in article gJWdnSvjUL6JNAvfRVn-rA@giganews.com, bhooshaniyer at
> bhooshaniyer@gmail.com wrote on 05/27/2005 00:59:
> 
> 
>>>Should any political party attempt to abolish Social Security,
>>>unemployment insurance, and eliminate labor laws and farm programs,
>>>you would not hear of that party again in our political history.
>>>There is a tiny splinter group, of course, that believes that you can
>>>do these things.  Among them are a few Texas oil millionaires, and an
>>>occasional politician or businessman from other areas.  Their number
>>>is negligible, and they are stupid.
>>>- Pres. Dwight D. Eisenhower, November 8, 1954
>>
>>Wow! Please dont be telling me that you did not make that one up?!
>>If thats not prophecy, tell me what is! Hair raising stuff.
> 
> 
> Every gun that is made, every warship launched, every rocket fired,
> signifies in the final sense a theft from those who hunger and are not fed,
> those who are cold and are not clothed.
> 
> Controlled, universal disarmament is the imperative of our time. The demand
> for it by the hundreds of millions whose chief concern is the long future of
> themselves and their children will, I hope, become so universal and so
> insistent that no man, no government anywhere, can withstand it.
> 
> Here in America we are descended in blood and in spirit from revolutionists
> and rebels - men and women who dare to dissent from accepted doctrine. As
> their heirs, may we never confuse honest dissent with disloyal subversion.
> 
> I hate war as only a soldier who has lived it can, only as one who has seen
> its brutality, its futility, its stupidity.
> 
> I like to believe that people in the long run are going to do more to
> promote peace than our governments. Indeed, I think that people want peace
> so much that one of these days governments had better get out of the way and
> let them have it. 
> 
> In the councils of government, we must guard against the acquisition of
> unwarranted influence, whether sought or unsought, by the
> military-industrial complex. The potential for the disastrous rise of
> misplaced power exists and will persist.

Add one of the simplest: "Beware of the military-industrial complex."

Jerry
-- 
Engineering is the art of making what you want from things you can get.
�����������������������������������������������������������������������

in article 2vOdncbA368MvArfRVn-sg@giganews.com, bhooshaniyer at
bhooshaniyer@gmail.com wrote on 05/27/2005 09:33:

 
> Wow! Cool Stuff, was this guy a soldier by any chance? Seems like it!

this isn't just U.S. history (which you should not be expected to be fluent
in), but it's world history.  what MacArthur was in the Pacific theatre of
WW2, Eisenhower was of the European theatre.  maybe check your WW2 history.

-- 

r b-j                  rbj@audioimagination.com

"Imagination is more important than knowledge."

in article peCdnYHkm7cMuwrfRVn-sg@rcn.net, Jerry Avins at jya@ieee.org wrote
on 05/27/2005 09:54:

>> In the councils of government, we must guard against the acquisition of
>> unwarranted influence, whether sought or unsought, by the
>> military-industrial complex. The potential for the disastrous rise of
>> misplaced power exists and will persist.
> 
> Add one of the simplest: "Beware of the military-industrial complex."

i actually was looking for something like that (Googled Eisenhower with
"military-industrial complex" together).  i think that phrase is a
distillation of the one that i quoted, but, of course, i cannot be sure.  i
was _born_ when Eisenhower was prez, you probably remember these quotes
first hand.

-- 

r b-j                  rbj@audioimagination.com

"Imagination is more important than knowledge."

in article 2vOdncbA368MvArfRVn-sg@giganews.com, bhooshaniyer at
bhooshaniyer@gmail.com wrote on 05/27/2005 09:33:

> I blame the dems for being so pussilanamous, so cowardly and so not sure
> about their philosiphies. They are so scared about being branded anti-war,
> hence anti-american. I despise them for having no courage to stand up and
> state *anything* but would resort to whining and fillibuster elsewhere.
> They present no alternative at this point nor will they present any time
> in the future,unless someone rises from the ranks and speaks with a moral
> authority so powerful and vision so clear that makes the regula american
> feel that he is being represented in the true sense of the word.
> 
> The future of the democrats is so bleak and so disastorous that somehow I
> wish that America was not a two party system or still better I wish
> America was ready for Coalition politics much like the Indian and Eurpoean
> 21st century. But for sure the democratic future is not in the kennedy's,
> the boxers, the deans, the edwards, the clintons, (am thinking now and I
> cant recollect the Democratic Presidential Candiate's name!)- that guy,
> george soros, michael moore etc. THE man or woman is just not around the
> corner. And thats bad news for Americans and the world.
> 
> I see nothing stopping Rudi Guilliani.

Bill Frist?

> 
> ps:As someone said, Hillary seems to have more balls than the entire dem
> boys put together, but unfortunately she is stuck at partial birth
> abortions and gay marraige and her husbands UN nomination etc.

listen, i was a big Howard Dean supporter (i actually got to introduce the
candidate to a town-hall meeting in Wentsworth NH Jan 24 2004 just before
the NH primary).  you need not convince me of the lack of spine of the
party.  but they did gang up on him and his front-runner status went down in
flames.

i know Edwards will be running in 2008.  i think there will be too much
baggage for Hillery to run successfully.  i'm thinking the sleeper
Democratic candidate will be Sen. Byron Dorgan of North Dakota.  solid
moderate progressive credentials from a solid red state, and he's
squeaky-clean to boot.

-- 

r b-j                  rbj@audioimagination.com

"Imagination is more important than knowledge."