refactor: update variables and docs

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---

Author: kgryte

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

@@ -97,9 +97,9 @@ var cfftb1 = require( './cfftb1.js' );
 *     where `i = sqrt(-1)`.
 *
 * @param {NonNegativeInteger} N - length of the sequence to transform
-* @param {Float64Array} c - input array containing the sequence to be transformed
+* @param {Float64Array} c - real-valued input array containing interleaved real and imaginary components corresponding to the sequence to be transformed
 * @param {NonNegativeInteger} offsetC - starting index for `c`
-* @param {Float64Array} wsave - workspace array containing pre-computed values
+* @param {Float64Array} wsave - real-valued workspace array containing pre-computed values
 * @param {NonNegativeInteger} offsetW - starting index for `wsave`
 * @returns {void}
 *

lib/node_modules/@stdlib/fft/base/fftpack/lib/cfftb1.js

@@ -62,6 +62,7 @@
 
 // MODULES //
 
+var floor = require( '@stdlib/math/base/special/floor' );
 var passb4 = require( './passb4.js' );
 var passb2 = require( './passb2.js' );
 var passb3 = require( './passb3.js' );
@@ -75,18 +76,18 @@ var passfb = require( './passfb.js' );
 * Performs the backward complex Fourier transform (i.e., the Fourier synthesis).
 *
 * @private
-* @param {number} n - length of the sequence to transform
-* @param {Float64Array} c - input array containing sequence to be transformed
-* @param {NonNegativeInteger} cOffset - starting index for input array
-* @param {Float64Array} ch - working array for intermediate results
-* @param {NonNegativeInteger} chOffset - starting index for working array
-* @param {Float64Array} wa - array of twiddle factors
-* @param {NonNegativeInteger} waOffset - starting index for twiddle factors array
-* @param {Int32Array} ifac - array containing factorization information
-* @param {NonNegativeInteger} ifacOffset - starting index for factorization array
+* @param {number} N - length of the sequence to transform
+* @param {Float64Array} c - real-valued input array containing interleaved real and imaginary components corresponding to the sequence to be transformed
+* @param {NonNegativeInteger} cOffset - starting index for `c`
+* @param {Float64Array} ch - workspace array for storing intermediate results
+* @param {NonNegativeInteger} chOffset - starting index for `ch`
+* @param {Float64Array} wa - workspace array for storing twiddle factors
+* @param {NonNegativeInteger} waOffset - starting index for `wa`
+* @param {Int32Array} ifac - workspace array for storing factorization information
+* @param {NonNegativeInteger} ifacOffset - starting index for `ifac`
 * @returns {void}
 */
-function cfftb1( n, c, cOffset, ch, chOffset, wa, waOffset, ifac, ifacOffset ) {
+function cfftb1( N, c, cOffset, ch, chOffset, wa, waOffset, ifac, ifacOffset ) {
 	var idl1;
 	var idot;
 	var ix2;
@@ -110,7 +111,7 @@ function cfftb1( n, c, cOffset, ch, chOffset, wa, waOffset, ifac, ifacOffset ) {
 	for ( k1 = 1; k1 <= nf; k1++ ) {
 		ip = ifac[ ifacOffset+k1+1 ];
 		l2 = ip * l1;
-		ido = n / l2;
+		ido = floor( N / l2 );
 		idot = ido + ido;
 		idl1 = idot * l1;
 		switch ( ip ) {
@@ -148,12 +149,13 @@ function cfftb1( n, c, cOffset, ch, chOffset, wa, waOffset, ifac, ifacOffset ) {
 			break;
 		}
 		l1 = l2;
-		iw += ( ip - 1 ) * idot;
+		iw += ( ip-1 ) * idot;
 	}
 	if ( na === 0 ) {
 		return;
 	}
-	for ( i = 0; i < n*2; i++ ) {
+	// Now that we've finished computing the transforms, copy over the final results to the input array...
+	for ( i = 0; i < N*2; i++ ) {
 		c[ i+cOffset ] = ch[ i+chOffset ];
 	}
 }