Apply a digital filter (direct form II transposed): Difference between revisions

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 =={{header|ALGOL 68}}==
 {{Trans|C++}} ... via Yabasic<br>
+... with the "j" loops transformed to not needlessly iterate beyond i.<br>
 The default lower bound in Algol 68 arrays is 1, so the loops/subscripts have been adjusted accordingly.
-<syntaxhighlight lang="algol68">BEGIN # apply a digital filter #
+<syntaxhighlight lang="algol68">
+BEGIN # apply a digital filter #
+    # the lower bounds of a, b, signal and result must all be equal #
     PROC filter = ( []REAL a, b, signal, REF[]REAL result )VOID:
          BEGIN
@@ Line 121: / Line 124: @@
             FOR i FROM LWB signal TO UPB signal DO
                 REAL tmp := 0;
-                FOR j FROM LWB b TO UPB b DO
+                FOR j FROM LWB b TO IF i > UPB b THEN UPB b ELSE i FI DO
-                    IF i >= j THEN tmp +:= b[ j ] * signal[ LWB signal + ( i - j ) ] FI
+                    tmp +:= b[ j ] * signal[ LWB signal + ( i - j ) ]
                 OD;
-                FOR j FROM LWB a TO UPB a DO
+                FOR j FROM LWB a + 1 TO IF i > UPB a THEN UPB a ELSE i FI  DO
-                    IF i >= j THEN tmp -:= a[ j ] * result[ LWB result + ( i - j ) ] FI
+                    tmp -:= a[ j ] * result[ LWB result + ( i - j ) ]
                 OD;
                 result[ i ] := tmp / a[ LWB a ]
@@ Line 145: / Line 148: @@
         IF i MOD 5 /= 0 THEN print( ( ", " ) ) ELSE print( ( newline ) ) FI
     OD
+END
-END</syntaxhighlight>
+</syntaxhighlight>
 {{out}}
 <pre>
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  -0.211722,  -0.174746,   0.069258,   0.385446,   0.651771
 </pre>
 =={{header|AppleScript}}==
 {{trans|Julia}} — except that j starts from 2 in the second inner repeat, there being no point in fetching and performing math with the zero about to be overwritten. This change in turn allows the result list to be populated on the fly instead of being pre-populated with zeros.