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有没有学气象的？或者谁知道在matlab上实现带通滤波。我想求滤除30~50天低频振荡的波的程序。
for程序：我想问问能不能在matlab上用呢？
PROGRAM TEST
C---------------------30-60 DAYS FILTER PROGRAM-----------------------
C
C ********PARAMETER EXPLANATION*********
C
C X(ND)-----INPUT SERIES
C ND -----LENTH OF SERIES
C W0 -----CENTER FREQUENCE
C W1 -----LEFT FREQUENCE
C Y(ND)-----OUTPUT SERIES
C
C---------------------30-50 DAYS FILTER PROGRAM-----------------------
c
c************************************************************************
c compute the boundery (grid number) and the total grids of the
c selected sub-region
c
c j=29, 50N -|----------------------------------|
c | |
c | |
c | |
c | |
c | |
c j=1 -20S -|----------------------------------|
c 40E 180E
c i=1 i=61
c*************************************************************************
PARAMETER(ND=366,R1=1.0E-02,R2=1.0E+02)
parameter(nx=144,ny=73)
DIMENSION X1(ND),Y1(ND)
dimension x(nx,ny,nd),y(nx,ny,nd)
C
C------------------------------------------------
open(1,file='d:\shuju\hgt.2000std.grd',status='old',
& form='unformatted',recl=nx*ny,access='direct')
irec=1
do 222 k=1,nd
read(1,rec=irec) ((x(i,j,k),i=1,nx),j=1,ny)
irec=irec+1
222 continue
write(*,*) 'recl=',irec-1
close(1)
c
c------------------------
DO 30 I=1,nx
DO 30 J=1,ny
DO 35 IT=1,ND
X1(IT)=X(I,J,IT)
35 CONTINUE
CALL FILTER(X1,ND,W0,W1,Y1)
DO 25 IT=1,ND
Y(I,J,IT)=Y1(IT)
* ratio(i,j,it)=x(i,j,it)/y(i,j,it)
25 CONTINUE
30 CONTINUE
c
c----------------------------
open(2,file='d:\shuju\hgt.2000stdf.grd',
& form='unformatted',recl=nx*ny,access='direct')
ir=1
do 91 k=1,ND
write(2,rec=ir) ((y(i,j,k),i=1,nx),j=1,ny)
ir=ir+1
91 continue
close(2)
* open(3,file='e:\data2\d.u8\ratio1998.dat',
* * form='unformatted',recl=nx*ny*4,access='direct')
* ir=1
* do 92 k=1,ND
* write(3,rec=ir) ((ratio(i,j,k),i=1,nx),j=1,ny)
* ir=ir+1
* 92 continue
* write(*,*)(ratio(80,75,k),k=1,365)
* close(3)
STOP
END
c
c
CCCC ****THE FOLLOWING IS FOR BEING QUASI-40-DAYS BAND-FILTED*****
c
SUBROUTINE FILTER(WK,ND,W0,W1,Y)
DIMENSION W(400),WK(ND),WK1(400),WK2(400),Y(ND)
REAL SW,SWT,SWT2,S
DT=1.0
PERC=42.42
PERL=30
PI2=2.0*3.14159
W0=PI2/PERC
W0S=W0*W0
W1=PI2/PERL
W2=W0S/W1
DW0=(SIN(W1*DT))/(1.+COS(W1*DT))-(SIN(W2*DT))/(1.+COS(W2*DT))
DW=2.*ABS(DW0)
DWS=(4.*SIN(W1*DT)*SIN(W2*DT))/((1.+COS(W1*DT))*(1.+COS(W2*DT)))
B3=(2.*DW)/(4.+2.*DW+DWS)
B2=(4.-2.*DW+DWS)/(4.+2.*DW+DWS)
B1=(2.0*(DWS-4.))/(4.+2.*DW+DWS)
S=0.0
c-----------------------
c
DO 111 IT=1,ND
ST=WK(IT)
S=S+ST
111 CONTINUE
c--------------------------
c
S=S/FLOAT(ND)
DO 112 IT=1,ND
WK(IT)=WK(IT)-S
112 CONTINUE
c-----------------------
c
ST=0.0
ST2=0.0
ST3=0.0
ST4=0.0
SW=0.0
SWT=0.0
SWT2=0.0
c--------------------------
c
DO 113 IT=1,ND
ST=ST+FLOAT(IT-ND/2)
ST2=ST2+(FLOAT(IT-ND/2))**2
ST3=ST3+(FLOAT(IT-ND/2))**3
ST4=ST4+(FLOAT(IT-ND/2))**4
SW=SW+WK(IT)
SWT=SWT+WK(IT)*FLOAT(IT-ND/2)
SWT2=SWT2+WK(IT)*(FLOAT(IT-ND/2))**2
113 CONTINUE
c------------------------------
c
R=-((ST2)**3-2.0*ST*ST2*ST3-ND*ST2*ST4+ST4*ST**2+ST3**2*ND)
A=(SWT2*ST2*ST2-ST*ST3*SWT2+ST*SWT*ST4-SWT*ST3*ST2+ST3*ST3*SW-
& SW*ST2*ST4)/R
B=(ST2*SWT*ST2-SW*ST3*ST2+ST*SW*ST4-ST*SWT2*ST2+ST3*SWT2*ND-
& ND*SWT*ST4)/R
C=(ST2*SW*ST2-SWT*ST*ST2+ST*ST*SWT2-ST*SW*ST3+ST3*SWT*ND-
& ND*SWT2*ST2)/R
c-----------------------------
c
DO 333 IT=1,ND
W(IT)=A+B*FLOAT(IT-ND/2)+C*(FLOAT(IT-ND/2))**2
WK(IT)=WK(IT)-W(IT)
333 CONTINUE
c---------------------------
c
ITXM=ND-1
DO 32 IT=1,ND
WK1(IT)=0.0
32 CONTINUE
c---------------------------
c
DO 36 IT=3,ND
WK1(IT)=B3*(WK(IT)-WK(IT-2))-B1*WK1(IT-1)-B2*WK1(IT-2)
36 CONTINUE
c-----------------------------
c
WK2(ND-1)=WK1(ND-1)
WK2(ND)=WK1(ND)
WK1(1)=WK(1)
WK1(2)=WK(2)
c-------------------------
c
DO 34 IT=2,ITXM
II=ND-IT
WK2(II)=B3*(WK1(II)-WK1(II+2))-B1*WK2(II+1)-B2*WK2(II+2)
34 CONTINUE
c---------------------------
c close(21)
DO 37 IT=1,ND
Y(IT)=WK2(IT)
37 CONTINUE
RETURN
END |
发表于 2007-4-22 09:41
提升卡
变色卡
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发表于 2007-4-23 08:49
