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Multi-Phase Power-Sinusoids 1: Introduction

Multi-phase power-sinusoids are not yet in the textbooks. They generalize , , and to by introducing extra parameters: the number of phases , the phase index , the power , together with the quantity . The factor is the selector for the phase (just as selects and selects ). The numbers and are integration constants. They are kept at 0 in this Demonstration.
Sinusoids are developed as solutions to differential equations in Multi-Phase Power Sinusoids 2: Differential Equations, and as modified exponential series in Multi-Phase Power-Sinusoids 3: Exponential Series.
When and , the traditional functions and are the differences between pairs of phases (Thumbnail, Fig. 1), that is, ; as the second term is the negation of the first, the amplitude is twice that of the phases and the integration constants cancel (giving a static zero mean). The functions and are not symmetrical; and are "missing phases". This is because is a cyclotomic number with and ; in contrast, the powers are independent unsigned directions so there are four different phases.
Now look at the first snapshot (Fig. 2.3), which shows the 3-phase sinusoid. Change . Note that odd powers always sum to zero. Do you think that their absolute values can sum to a constant? When do you think that even powers sum to a constant? This topic is explored in Multi-Phase Power-Sinusoid 4: Summations.
Now look at snapshot 2 (Fig. 2.4). (Half the phases are displaced slightly when and are both even to show superimposition.) Higher numbers of phases and powers are shown in later snapsots. They follow the convention of projecting the phases onto the same - plane. Multi-Phase Power-Sinusoids 5: Helices and Pulses shows other projections; three-dimensional -- helices, -dimensional trajectories, and wave-packets (modulations of travelling pulses).

SNAPSHOTS

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DETAILS

(Euler's formula) expresses sinusoids as the odd or even terms of the series , where even powers of become . This is generalized by replacing with (an independent direction, not a complex cyclotomic number) to give
, with (See Multi-Phase Power-Sinusoids 3 for details.)
Summing every term of this series, starting with the , gives separate phases (each multiplied by a direction ). The sums of the terms of grow exponentially unless . This growth can be eliminated by including a normalizing factor, replacing by , with . The amplitude is set to 1/2 so that the difference between odd (or even) phases matches the amplitude of (or ).
Mathematica expresses roots of unity as complex cyclotomic numbers. This is generalized to multiple independent roots of unity (these occur in some Clifford and Hoop algebras). This does not cause problems at this level as and can be calculated as and .
Multi-Phase Power Sinusoids 2: Differential Equations shows multi-phase power-sinusoids as solutions to banded sets of differential equations. Their period is greater than unless . The period is for and 6, and (half spin) for .
Multi-Phase Power-Sinusoids 3: Exponential Series demonstrates phases as the sums of every member of the stable infinite power series . Truncating the series introduces exponentially growing errors.
Multi-Phase Power-Sinusoids 4: Summations investigates the properties of the sums of all phases (or their absolute values for odd powers, when the sums are zero). The sum of the even powers is a constant for some small values of (the helix identity), generalizing and leading to some conserved properties.
Multi-Phase Power-Sinusoids 5: Helices and Pulses introduces helices and modulated pulses, showing that phases can act as orthogonal fields and multi-phase wave packets.
Multi-Phase Power-Sinusoids 6: Non-integer Powers shows that need not be an integer, though integration then creates compactons having support over a narrow range.
The author discovered multi-phase power sinusoids in 2000. He discovered the helix identity empirically in 2001 and published a brief description in this Google Group posting. The binomial formulation and limits were supplied by J. J. Thwaites on 26/9/2002. His lemma was extended to include harmonics by G. Gerrard in July 2011 (personal communications).








 
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