forked from SLICOT/SLICOT-Reference
-
Notifications
You must be signed in to change notification settings - Fork 1
Expand file tree
/
Copy pathDK01MD.f
More file actions
165 lines (165 loc) · 4.1 KB
/
Copy pathDK01MD.f
File metadata and controls
165 lines (165 loc) · 4.1 KB
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
SUBROUTINE DK01MD( TYPE, N, A, INFO )
C
C PURPOSE
C
C To apply an anti-aliasing window to a real signal.
C
C ARGUMENTS
C
C Mode Parameters
C
C TYPE CHARACTER*1
C Indicates the type of window to be applied to the signal
C as follows:
C = 'M': Hamming window;
C = 'N': Hann window;
C = 'Q': Quadratic window.
C
C Input/Output Parameters
C
C N (input) INTEGER
C The number of samples. N >= 1.
C
C A (input/output) DOUBLE PRECISION array, dimension (N)
C On entry, this array must contain the signal to be
C processed.
C On exit, this array contains the windowing function.
C
C Error Indicator
C
C INFO INTEGER
C = 0: successful exit;
C < 0: if INFO = -i, the i-th argument had an illegal
C value.
C
C METHOD
C
C If TYPE = 'M', then a Hamming window is applied to A(1),...,A(N),
C which yields
C _
C A(i) = (0.54 + 0.46*cos(pi*(i-1)/(N-1)))*A(i), i = 1,2,...,N.
C
C If TYPE = 'N', then a Hann window is applied to A(1),...,A(N),
C which yields
C _
C A(i) = 0.5*(1 + cos(pi*(i-1)/(N-1)))*A(i), i = 1,2,...,N.
C
C If TYPE = 'Q', then a quadratic window is applied to A(1),...,
C A(N), which yields
C _
C A(i) = (1 - 2*((i-1)/(N-1))**2)*(1 - (i-1)/(N-1))*A(i),
C i = 1,2,...,(N-1)/2+1;
C _
C A(i) = 2*(1 - ((i-1)/(N-1))**3)*A(i), i = (N-1)/2+2,...,N.
C
C REFERENCES
C
C [1] Rabiner, L.R. and Rader, C.M.
C Digital Signal Processing.
C IEEE Press, 1972.
C
C NUMERICAL ASPECTS
C
C The algorithm requires 0( N ) operations.
C
C CONTRIBUTOR
C
C Release 3.0: V. Sima, Katholieke Univ. Leuven, Belgium, Feb. 1997.
C Supersedes Release 2.0 routine DK01AD by R. Dekeyser, State
C University of Gent, Belgium.
C
C REVISIONS
C
C -
C
C KEYWORDS
C
C Digital signal processing, Hamming window, Hann window, real
C signals, windowing.
C
C ******************************************************************
C
C .. Parameters ..
DOUBLE PRECISION PT46, HALF, PT54, ONE, TWO, FOUR
PARAMETER ( PT46=0.46D0, HALF=0.5D0, PT54=0.54D0,
$ ONE = 1.0D0, TWO=2.0D0, FOUR=4.0D0 )
C .. Scalar Arguments ..
CHARACTER TYPE
INTEGER INFO, N
C .. Array Arguments ..
DOUBLE PRECISION A(*)
C .. Local Scalars ..
LOGICAL MTYPE, MNTYPE, NTYPE
INTEGER I, N1
DOUBLE PRECISION BUF, FN, TEMP
C .. External Functions ..
LOGICAL LSAME
EXTERNAL LSAME
C .. External Subroutines ..
EXTERNAL XERBLA
C .. Intrinsic Functions ..
INTRINSIC ATAN, COS, DBLE
C .. Executable Statements ..
C
INFO = 0
MTYPE = LSAME( TYPE, 'M' )
NTYPE = LSAME( TYPE, 'N' )
MNTYPE = MTYPE.OR.NTYPE
C
C Test the input scalar arguments.
C
IF( .NOT.MNTYPE .AND. .NOT.LSAME( TYPE, 'Q' ) )
$ THEN
INFO = -1
ELSE IF( N.LE.0 ) THEN
INFO = -2
END IF
C
IF ( INFO.NE.0 ) THEN
C
C Error return.
C
CALL XERBLA( 'DK01MD', -INFO )
RETURN
END IF
C
FN = DBLE( N-1 )
IF( MNTYPE ) TEMP = FOUR*ATAN( ONE )/FN
C
IF ( MTYPE ) THEN
C
C Hamming window.
C
DO 10 I = 1, N
A(I) = A(I)*( PT54 + PT46*COS( TEMP*DBLE( I-1 ) ) )
10 CONTINUE
C
ELSE IF ( NTYPE ) THEN
C
C Hann window.
C
DO 20 I = 1, N
A(I) = A(I)*HALF*( ONE + COS( TEMP*DBLE( I-1 ) ) )
20 CONTINUE
C
ELSE
C
C Quadratic window.
C
N1 = ( N-1 )/2 + 1
C
DO 30 I = 1, N
BUF = DBLE( I-1 )/FN
TEMP = BUF**2
IF ( I.LE.N1 ) THEN
A(I) = A(I)*( ONE - TWO*TEMP )*( ONE - BUF )
ELSE
A(I) = A(I)*TWO*( ONE - BUF*TEMP )
END IF
30 CONTINUE
C
END IF
C
RETURN
C *** Last line of DK01MD ***
END