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2.3.4 ¸´Ö¸ÊýÐòÁÐ

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Im{f (k )}= rk sin(wk)Ϊf?k?µÄÐ鲿

¿É¼û£¬¸´Ö¸ÊýÐòÁÐf?k?µÄʵ²¿ºÍÐ鲿·Ö±ðΪ·ù¶È°´Ö¸Êý¹æÂɱ仯µÄÕýÏÒÐòÁС£µ±r£¾1ʱ£¬f?k?µÄʵ²¿ºÍÐ鲿·Ö±ðΪָÊýÔö³¤µÄÕýÏÒÐòÁУ»µ±0£¼r£¼1ʱ£¬f?k?µÄʵ²¿ºÍÐ鲿·Ö±ðΪָÊýË¥¼õµÄÕýÏÒÐòÁУ»µ±r?1ʱ£¬f?k?µÄʵ²¿ºÍÐ鲿·Ö±ðΪµÈ·ùÕýÏÒÐòÁС£

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function dfzsu?n1,n2,r,w? %n1:»æÖƲ¨ÐεÄÐéÖ¸ÊýÐòÁÐµÄÆðʼʱ¼äÐòºÅ

%n2£º»æÖƲ¨ÐεÄÐéÖ¸ÊýÐòÁеÄÖÕֹʱ¼äÐòºÅ %w£ºÐéÖ¸ÊýÐòÁÐµÄ½ÇÆµÂÊ %r: Ö¸ÊýÐòÁеĵ×Êý

k?n1:n2;

f?(r*exp(i*w))k;

Xr?real?f?; Xi?imag?f?; Xa?abs?f?; Xn?angle?f?;

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2.4 Àëɢʱ¼äÐòÁоí»ýºÍ¼°MATLABʵÏÖ

Àëɢʱ¼äÐòÁÐf1(k) ºÍf2(k)µÄ¾í»ýºÍ¶¨ÒåΪ:

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MATLABµÄconv()º¯Êý¿ÉÒÔ°ïÖúÎÒÃÇ¿ìËÙÇó³öÁ½¸öÀëÉ¢ÐòÁеľí»ýºÍ¡£convº¯ÊýµÄµ÷ÓøñʽΪ£ºf ? conv ?f1,f2?

ÆäÖÐf1Ϊ°üº¬ÐòÁÐf1(k)µÄ·ÇÁãÑùÖµµãµÄÐÐÏòÁ¿£¬f2Ϊ°üº¬ÐòÁÐf2(k)µÄ·ÇÁãÑùÖµµãµÄÐÐÏòÁ¿£¬ÏòÁ¿fÔò·µ»ØÐòÁÐset?gca,'position',h?µÄËùÓзÇÁãÑùÖµµãÐÐÏòÁ¿¡£

ÏÂÃæÊÇÀûÓÃMATLAB¼ÆËãÁ½ÀëÉ¢ÐòÁоí»ýºÍf(k)?f1(k)*f2(k)µÄʵÓú¯Êýdconv? ?£¬¸Ã³ÌÐòÔÚ¼ÆËã³ö¾í»ýºÍf(k)µÄͬʱ£¬»¹»æ³öÐòÁÐf1(k) ¡¢f2(k)ºÍf(k)µÄʱÓò²¨ÐÎͼ£¬²¢·µ»Øf(k)µÄ·ÇÁãÑùÖµµãµÄ¶ÔÓ¦ÏòÁ¿¡£

function ?f,k??dconv?f1,f2,k1,k2? % The function of compute f?f1*f2

% f: ¾í»ýºÍÐòÁÐf(k)¶ÔÓ¦µÄ·ÇÁãÑùÖµÏòÁ¿ % k£º ÐòÁÐf(k)µÄ¶ÔÓ¦ÐòºÅÏòÁ¿ % f1: ÐòÁÐf1(k)·ÇÁãÑùÖµÏòÁ¿ % f2: ÐòÁÐf2(k)µÄ·ÇÁãÑùÖµÏòÁ¿ % k1: ÐòÁÐf1(k)µÄ¶ÔÓ¦ÐòºÅÏòÁ¿ % k2: ÐòÁÐf2(k)µÄ¶ÔÓ¦ÐòºÅÏòÁ¿

f?conv?f1,f2? %¼ÆËãÐòÁÐf1Óëf2µÄ¾í»ýºÍf k0?k1?1??k2?1?; %¼ÆËãÐòÁÐf·ÇÁãÑùÖµµÄÆðµãλÖà k3?length?f1??length?f2??2; %¼ÆËã¾í»ýºÍfµÄ·ÇÁãÑùÖµµÄ¿í¶È

k?k0:k0?k3 %È·¶¨¾í»ýºÍf·ÇÁãÑùÖµµÄÐòºÅÏòÁ¿

stem?k1,f1?

stem?k1,f1? %ÔÚ×Óͼ1»æÐòÁÐf1(k)ʱÓò²¨ÐÎͼ title?'f1?k?'? xlabel?'k'? ylabel?'f1?k?'? subplot?2,2,2?

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stem?k,f?; %ÔÚ×Óͼ3»æÐòÁÐf(k)µÄ²¨ÐÎͼ title('f?k?f1?k?Óëf2?k?µÄ¾í»ýºÍf?k?')xlabel?'k'? ylabel?'f?k?'?

h?get?gca,'position'?; h?3??2.5*h?3?;

set?gca,'position',h? %½«µÚÈý¸ö×ÓͼµÄºá×ø±ê·¶Î§À©ÎªÔ­À´µÄ2.5±¶

2.5 ÀëɢϵͳµÄµ¥Î»ÏìÓ¦¼°MATLABʵÏÖ

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