public?final?class?FFT?{
	public?int?logm;
	final?int?MAXLOGM?=?20;?/*?max?FFT?length?2^MAXLOGM?*/
	final?double?TWOPI?=?6.28318530717958647692;
	final?double?SQHALF?=?0.707106781186547524401;
	int?brseed[]?=?new?int[4048];
	float?tab[][];

	public?FFT（int?nlength）?{
		double?dtemp?=?Math.log（nlength）?/?Math.log（2）;
		if?（（dtemp?-?（int）?dtemp）?!=?0.0）?{
			throw?new?Error（“FFT?length?must?be?a?power?of?2.“）;
		}?else?{
			this.logm?=?（int）?dtemp;
		}
		if?（logm?>=?4）?{
			creattab（logm）;
		}
	}

	/**
	?*?Calculates?the?magnitude?spectrum?of?a?real?signal.?The?returned?vector
	?*?contains?only?the?positive?frequencies.
	?*/
	public?float[]?calculateFFTMagnitude（float?x[]）?{
		int?i?n;
		n?=?1?<
		if?（x.length?>?n）?{
			throw?new?Error（“Tried?to?use?a?“?+?n
					+?“-points?FFT?for?a?vector?with?“?+?x.length?+?“?samples!“）;
		}

		rsfft（x）;

		float[]?mag?=?new?float[n?/?2?+?1];
		mag[0]?=?x[0];?//?DC?frequency?must?be?positive?always

		if?（n?==?1）?{
			return?mag;
		}
		mag[n?/?2]?=?（float）?Math.abs（x[n?/?2]）;?//?pi?（meaning:?fs?/?2）

		//?System.out.println（“FFT?before?magnitude“）;
		//?IO.DisplayVector（x）;

		for?（i?=?1;?i?			mag[i]?=?（float）?Math.sqrt（x[i]?*?x[i]?+?x[n?-?i]?*?x[n?-?i]）;
			//?System.out.println（mag[i]?+?“?“?+?x[i]?+?“?“?+?x[n-i]）;
		}

		//?IO.DisplayVector（mag）;
		return?mag;
	}

	/**
	?*?Calculates?the?magnitude?spectrum?of?a?real?signal.?The?returned?vector
	?*?contains?only?the?positive?frequencies.
	?*/
	public?double[]?calculateFFTMagnitude（double?inputData[]）?{
		int?i?n;
		n?=?1?<		if?（inputData.length?>?n）?{
			throw?new?Error（“Tried?to?use?a?“?+?n
					+?“-points?FFT?for?a?vector?with?“?+?inputData.length
					+?“?samples!“）;
		}

		//?System.out.println（“magnitude?test“）;
		//?double[]?dtest?=?DSP.DFTMagnitude（inputData）;
		//?IO.DisplayVector（dtest）;

		float[]?x?=?new?float[n];
		for?（i?=?0;?i?			x[i]?=?（float）?inputData[i];
		}

		rsfft（x）;

		//?System.out.println（“FFT?before?magnitude“）;
		//?IO.DisplayVector（x）;

		double[]?mag?=?new?double[n?/?2?+?1];
		mag[0]?=?x[0];?//?DC?frequency?must?be?positive?always

		if?（n?==?1）?{
			return?mag;
		}
		mag[n?/?2]?=?Math.abs（x[n?/?2]）;?//?pi?（meaning:?fs?/?2）

		for?（i?=?1;?i?			mag[i]?=?Math.sqrt（x[i]?*?x[i]?+?x[n?-?i]?*?x[n?-?i]）;
			//?System.out.println（mag[i]?+?“?“?+?x[i]?+?“?“?+?x[n-i]）;
		}

		//?IO.DisplayVector（mag）;
		return?mag;
	}

	/**
	?*?Calculates?the?power?（magnitude?squared）?spectrum?of?a?real?signal.?The
	?*?returned?vector?contains?only?the?positive?frequencies.
	?*/
	public?double[]?calculateFFTPower（double?inputData[]）?{
		int?i?n;
		n?=?1?<
		//?System.out.println（“magnitude?test“）;
		//?double[]?dtest?=?DSP.DFTMagnitude（inputData）;
		//?IO.DisplayVector（dtest）;

		float[]?x?=?new?float[n];
		for?（i?=?0;?i?

?屬性????????????大小?????日期????時間???名稱
-----------?---------??----------?-----??----

?????文件??????17791??2012-03-08?19:25??MFCC.java

?????文件??????20160??2012-03-08?19:26??FFT.java

-----------?---------??----------?-----??----

????????????????37951????????????????????2