feat: add passb3

Author: gunjjoshi

lib/node_modules/@stdlib/fft/base/fftpack/lib/passb3.js

@@ -106,7 +106,41 @@ function passb3( ido, l1, cc, ch, wa1, wa2 ) {
 
 	// Function body:
 	if ( ido == 2 ) {
-
+		for ( k = 1; k <= l1; ++k ) {
+			tr2 = cc[ ccRef( 1, 2, k, 3, ido ) - cc_offset ] + cc[ ccRef( 1, 3, k, 3, ido ) - cc_offset ]; // eslint-disable-line max-len
+			cr2 = cc[ ccRef( 1, 1, k, 3, ido ) - cc_offset ] + ( taur * tr2 );
+			ch[ chRef( 1, k, 1, l1, ido ) - ch_offset ] = cc[ ccRef( 1, 1, k, 3, ido ) - cc_offset ] + tr2; // eslint-disable-line max-len
+			ti2 = cc[ ccRef( 2, 2, k, 3, ido ) - cc_offset ] + cc[ ccRef( 2, 3, k, 3, ido ) - cc_offset ]; // eslint-disable-line max-len
+			ci2 = cc[ ccRef( 2, 1, k, 3, ido ) - cc_offset ] + ( taur * ti2 );
+			ch[ chRef( 2, k, 1, l1, ido ) - ch_offset ] = cc[ ccRef( 2, 1, k, 3, ido ) - cc_offset ] + ti2; // eslint-disable-line max-len
+			cr3 = taui * ( cc[ ccRef( 1, 2, k, 3, ido ) - cc_offset ] - cc[ ccRef( 1, 3, k, 3, ido ) - cc_offset ] ); // eslint-disable-line max-len
+			ci3 = taui * ( cc[ ccRef( 2, 2, k, 3, ido ) - cc_offset ] - cc[ ccRef( 2, 3, k, 3, ido ) - cc_offset ] ); // eslint-disable-line max-len
+			ch[ chRef( 1, k, 2, l1, ido ) - ch_offset ] = cr2 - ci3;
+			ch[ chRef( 1, k, 3, l1, ido ) - ch_offset ] = cr2 + ci3;
+			ch[ chRef( 2, k, 2, l1, ido ) - ch_offset ] = ci2 + ci3;
+			ch[ chRef( 2, k, 3, l1, ido ) - ch_offset ] = ci2 - cr3;
+		}
+	} else {
+		for ( k = 1; k <= l1; ++k ) {
+			for ( i = 2; i <= ido; i += 2 ) {
+				tr2 = cc[ ccRef( i - 1, 2, k, 3, ido ) - cc_offset ] + cc[ ccRef( i - 1, 3, k, 3, ido ) - cc_offset ]; // eslint-disable-line max-len
+				cr2 = cc[ ccRef( i - 1, 1, k, 3, ido ) - cc_offset ] + ( taur * tr2 );
+				ch[ chRef( i - 1, k, 1, l1, ido ) - ch_offset ] = cc[ ccRef( i - 1, 1, k, 3, ido ) - cc_offset ] + tr2; // eslint-disable-line max-len
+				ti2 = cc[ ccRef( i, 2, k, 3, ido ) - cc_offset ] + cc[ ccRef( i, 3, k, 3, ido ) - cc_offset ]; // eslint-disable-line max-len
+				ci2 = cc[ ccRef( i, 1, k, 3, ido ) - cc_offset ] + ( taur * ti2 );
+				ch[ chRef( i, k, 1, l1, ido ) - ch_offset ] = cc[ ccRef( i, 1, k, 3, ido ) - cc_offset ] + ti2; // eslint-disable-line max-len
+				cr3 = taui * ( cc[ ccRef( i - 1, 2, k, 3, ido ) - cc_offset ] - cc[ ccRef( i - 1, 3, k, 3, ido ) - cc_offset ] ); // eslint-disable-line max-len
+				ci3 = taui * ( cc[ ccRef( i, 2, k, 3, ido ) - cc_offset ] - cc[ ccRef( i, 3, k, 3, ido ) - cc_offset ] ); // eslint-disable-line max-len
+				dr2 = cr2 - ci3;
+				dr3 = cr2 + ci3;
+				di2 = ci2 + ci3;
+				di3 = ci2 - cr3;
+				ch[ chRef( i, k, 2, l1, ido) - ch_offset ] = ( wa1[ i - 1 - 1 ] * di2 ) + ( wa1[ i - 1 ] * dr2 );
+				ch[ chRef( i - 1, k, 2, l1, ido) - ch_offset ] = ( wa1[ i - 1 - 1 ] * dr2 ) - ( wa1[ i - 1 ] * di2 );
+				ch[ chRef( i, k, 3, l1, ido) - ch_offset ] = ( wa2[ i - 1 - 1 ] * dr3 ) - ( wa2[ i - 1 ] * di3 );
+				ch[ chRef( i - 1, k, 3, l1, ido) - ch_offset ] = ( wa2[ i - 1 - 1 ] * dr3 ) - ( wa2[ i - 1 ] * di3 );
+			}
+		}
 	}
 }