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ijàãîíàëüíà ìàòðèöÿ, â ÿêî¿ âñ³ åëåìåíòè ãîëîâíî¿ ä³àãîíàë³<br />

äîð³âíþþòü îäèíèö³, íàçèâàºòüñÿ îäèíè÷íîþ ³ ïîçíà÷à-<br />

ºòüñÿ áóêâîþ Å (I)<br />

⎛1 0... 0⎞<br />

⎜ ⎟<br />

0 1 ... 0<br />

E = ⎜ ⎟<br />

⎜ ... ... ... ... ⎟ .<br />

⎜<br />

00...1⎟<br />

⎝ ⎠<br />

2.2.3. ij¿ íàä ìàòðèöÿìè<br />

Ñóìîþ äâîõ ìàòðèöü îäíàêîâèõ ðîçì³ð³â íàçèâàºòüñÿ<br />

ìàòðèöÿ òîãî æ ðîçì³ðó, åëåìåíòè ÿêî¿ äîð³âíþþòü ñóìàì<br />

â³äïîâ³äíèõ åëåìåíò³â äîäàíê³â ìàòðèöü.<br />

Çà îçíà÷åííÿì ñóìà ìàòðèöü À ³ Â<br />

º ìàòðèöÿ<br />

⎛a11 a12 ... a1 n ⎞ ⎛b11 b12 ... b1<br />

n ⎞<br />

⎜ ⎟ ⎜ ⎟<br />

a21 a22 ... a2n<br />

b21 b22 ... b2<br />

n<br />

A= ⎜ ⎟ B = ⎜ ⎟<br />

⎜... ... ... ... ⎟ ⎜... ... ... ... ⎟<br />

⎜ a a ... a ⎟ ⎜ b b ... b ⎟<br />

⎝ m1 m2 mn⎠ ⎝ m1 m2<br />

mn⎠<br />

⎛a + b a + b ... a + b<br />

⎜<br />

⎜<br />

a + b a + b ... a + b<br />

11 11 12 12 1n<br />

1n<br />

21 21 22 22 2n<br />

2n<br />

= + = ⎜ ... ... ... ... ⎟ (2.2.1)<br />

⎜<br />

am 1<br />

+ bm 1<br />

am2 + bm 2...<br />

amn + b ⎟<br />

⎝ mn ⎠ .<br />

C A B<br />

Î÷åâèäíî, ùî À +  =  + À; À +0=0+À = À.<br />

Ìàòðèö³ À ³ Â íàçèâàþòüñÿ ïðîòèëåæíèìè, ÿêùî ¿õ ñóìà<br />

À + Â =0 º íóëü-ìàòðèöÿ. Ìàòðèöÿ, ïðîòèëåæíà ìàòðèö³ À,<br />

ïîçíà÷àºòüñÿ –À, ³ ¿¿ åëåìåíòè ïðîòèëåæí³ çà çíàêîì åëåìåíòàì<br />

ìàòðèö³ À. Òîä³ ð³çíèöÿ äâîõ ìàòðèöü À ³  ìîæå<br />

áóòè çàì³íåíà ñóìîþ À ³ (–Â):<br />

C = À – Â = À +(–Â).<br />

Äîáóòêîì ìàòðèö³ íà ÷èñëî (àáî ÷èñëà íà ìàòðèöþ) íàçèâàºòüñÿ<br />

ìàòðèöÿ, åëåìåíòè ÿêî¿ º äîáóòêè åëåìåíò³â äàíî¿<br />

ìàòðèö³ íà öå ÷èñëî<br />

⎞<br />

⎟<br />

⎟<br />

⎛a11 a12 ... a1 n ⎞ ⎛λa11 λa12 ... λa1<br />

n ⎞<br />

⎜ ⎟ ⎜ ⎟<br />

a21 a22 ... a2n<br />

λa21 λa22 ... λa2n<br />

λ A= Aλ = λ ⎜ ⎟ = ⎜ ⎟<br />

⎜... ... ... ... ⎟ ⎜ ... ... ... ... ⎟.<br />

⎜ a a ... a ⎟ ⎜ λa λa ... λa<br />

⎟<br />

⎝ m1 m2 mn ⎠ ⎝ m1 m2<br />

mn ⎠<br />

Î÷åâèäí³ âëàñòèâîñò³: λ (À + Â) =λÀ + λÂ; À⋅0 =0⋅À =0.<br />

Ïîð³âíþþ÷è âèçíà÷åííÿ îïåðàö³é äîäàâàííÿ, â³äí³ìàííÿ<br />

³ ìíîæåííÿ ìàòðèöü íà ÷èñëî ç àíàëîã³÷íèìè îïåðàö³ÿìè<br />

íàä âåêòîðàìè, áà÷èìî ¿õ àíàëîã³þ.<br />

Äîáóòêîì äâîõ ìàòðèöü À ³  (÷èñëî ñòîâïö³â ïåðøî¿<br />

ìàòðèö³ ïîâèííî äîð³âíþâàòè ÷èñëó ðÿäê³â äðóãî¿ ìàòðèö³)<br />

íàçèâàºòüñÿ òðåòÿ ìàòðèöÿ C, ó ÿê³é åëåìåíò c ij äîð³âíþº<br />

ñóì³ äîáóòê³â åëåìåíò³â i-ãî ðÿäêà ìàòðèö³ À íà â³äïîâ³äí³<br />

åëåìåíòè j-ãî ñòîâïöÿ ìàòðèö³ Â, òîáòî<br />

{ }<br />

1 1<br />

C = A⋅ B = c , äå c = a b + ... + a b , i = 1, m, j = 1, p . (2.2.2)<br />

ij ij i j in nj<br />

ßêùî ìàòðèöÿ À ìຠðîçì³ð m×n,  — n × p, òî Ñ áóäå<br />

ìàòè ðîçì³ð m × p.<br />

Äâ³ ìàòðèö³ íàçèâàþòüñÿ ïîãîäæåíèìè, ÿêùî ÷èñëî<br />

ñòîâïö³â ïåðøî¿ ìàòðèö³ äîð³âíþº ÷èñëó ðÿäê³â äðóãî¿.<br />

Ïðèêëàä 2.2.1. Çíàéòè äîáóòîê ìàòðèöü<br />

123 ⎛7⎞<br />

⎛ ⎞ ⎜ ⎟<br />

A= ⎜ ⎟ i B = 8<br />

456<br />

⎝ ⎠<br />

.<br />

⎜9<br />

⎟<br />

⎝ ⎠<br />

Ðîçâ’ÿçàííÿ. Ö³ ìàòðèö³ ïîãîäæåí³ (ê³ëüê³ñòü ñòîâïö³â<br />

ìàòðèö³ À äîð³âíþº 3, à ê³ëüê³ñòü ðÿäê³â ìàòðèö³  òåæ<br />

äîð³âíþº 3). Çà âèçíà÷åííÿì äîáóòêó çíàõîäèìî<br />

⎛7⎞<br />

⎛123⎞⎜ ⎟ ⎛17 ⋅ + 28 ⋅ + 39 ⋅ ⎞ ⎛50⎞<br />

AB ⋅ = ⎜ ⎟ 8<br />

456 = ⎜ ⎟=<br />

⎜ ⎟<br />

⎝ ⎠ ⎝47 ⋅ + 58 ⋅ + 69 ⋅ ⎠ ⎝122⎠<br />

.<br />

⎜9⎟<br />

⎝ ⎠<br />

46 47

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