+ Post New Thread
Results 1 to 8 of 8

23rd May 2006, 09:17 #1
 Join Date
 Jan 2005
 Posts
 21
 Helped
 0 / 0
 Points
 1,570
 Level
 9
difference between laplace and fourier transform
What are the differences?
I mean when we will make a decision "hmm now i must use laplace transform or now i must use fourier transform".
What are the absences in laplace transform so fourier design a new transfom?
I want to know these transforms' main idea, differences.
I am looking for your answers.
Thanks .
Sincerely;

23rd May 2006, 09:17

23rd May 2006, 10:15 #2
 Join Date
 Nov 2004
 Location
 Tamilnadu
 Posts
 657
 Helped
 36 / 36
 Points
 5,970
 Level
 18
laplace vs fourier
for all signals we can have laplace transform but we can have fourier transform only for ceratin cases...Fourier transform needs certain conditions caled as Dirchlet conditions whereas laplace wont need anything like this....
1 members found this post helpful.

23rd May 2006, 11:07 #3
 Join Date
 Jan 2005
 Posts
 21
 Helped
 0 / 0
 Points
 1,570
 Level
 9
difference between laplace and fourier
Originally Posted by electronics_kumar
Thanks...

23rd May 2006, 11:07

23rd May 2006, 11:45 #4
 Join Date
 May 2006
 Posts
 4
 Helped
 2 / 2
 Points
 1,261
 Level
 8
fourier vs laplace
1 members found this post helpful.

23rd May 2006, 15:26 #5
 Join Date
 Dec 2004
 Location
 Iran
 Posts
 152
 Helped
 36 / 36
 Points
 2,487
 Level
 11
laplace vs. fourier
in a simple expression:
Laplas Transform does a real transformation on complex data but Fourier Tranform does a complex transformation on real data.
it means:
L(σ1+jω1)=σ2+jω2
F(ω1)=ω2<ω2
at the presence of some condition you can take the Fourier transformation by placing jω instead of s in Laplas tranform.

23rd May 2006, 15:26

23rd May 2006, 16:01 #6
 Join Date
 May 2006
 Posts
 6
 Helped
 2 / 2
 Points
 1,209
 Level
 7
laplace vs fourier transform
theoretically..laplace represents σ + jw and is in all of the splane while in fourier its only in the jw axis of this splane..so basically we are setting the real part of the exponenntial to 0 and hence
it will give you the features for steady state for a sinusoidal input
and in the case of laplace it will tel u for rising or fallin sinusoidal.
i hope that shud answer ur question..
2 members found this post helpful.

24th May 2006, 04:27 #7
 Join Date
 Mar 2006
 Location
 Culiacán, Sinaloa, Mexico
 Posts
 479
 Helped
 71 / 71
 Points
 3,875
 Level
 14
laplas transform
For a good explanation you can consult the book PLL, or Roland E. Best, that you can find in this forum.
As my colegees said Laplace transform translate f(t) to σ + ωi domain, while Fourier translate f(t) to w domain.
that means Laplace has information of time and frequency that's why we use to study transitory circuits. But Fourier dosn't have all the information i this case fase and wave forms only frecquency and amplitude.

24th May 2006, 10:07 #8
 Join Date
 Nov 2004
 Location
 Tamilnadu
 Posts
 657
 Helped
 36 / 36
 Points
 5,970
 Level
 18
fourier versus laplace
Originally Posted by shivamrules
for lapalce transform, it is (σ + jw) when you are going to Fourier transform it become (0 + jw )..i mean σ =0 no attenuation in the system...
+ Post New Thread
Please login