{"id":6982,"date":"2021-07-23T23:21:10","date_gmt":"2021-07-23T14:21:10","guid":{"rendered":"https:\/\/sasamath.com\/blog\/?page_id=6982"},"modified":"2021-08-02T22:18:38","modified_gmt":"2021-08-02T13:18:38","slug":"complex-numbers","status":"publish","type":"page","link":"https:\/\/sasamath.com\/blog\/invitation-to-calculus\/complex-numbers\/","title":{"rendered":"\ud589\ub82c\uacfc \ubcf5\uc18c\uc218"},"content":{"rendered":"
\n

\uc774 \uae00\uc740 \u300e\ubbf8\uc801\ubd84\ud559 \uccab\uac78\uc74c\u300f 0\uc7a5 5\uc808\uc758 \ub0b4\uc6a9\uc785\ub2c8\ub2e4.  (\ubbf8\uc801\ubd84\ud559 \uccab\uac78\uc74c \ucc28\ub840 \ubcf4\uae30<\/a>)<\/span><\/p>\n<\/div>\n

\ud589\ub82c\uacfc \ubcf5\uc18c\uc218\ub294 \ubcc4\uac1c\uc758 \uac1c\ub150\uc778 \uac83\ucc98\ub7fc \ubcf4\uc774\uc9c0\ub9cc \uc0ac\uc2e4 \ubc00\uc811\ud55c \uc5f0\uad00\uc774 \uc788\ub2e4. \uc774 \uc808\uc5d0\uc11c\ub294 \\(2\\times 2\\) \ud589\ub82c\uacfc \ubcf5\uc18c\uc218\ub97c \uc0b4\ud3b4\ubcf4\uc790.<\/p>\n

<\/p>\n

\ud589\ub82c<\/h2>\n

\ud589\ub82c<\/span>(matrix)\uc774\ub780 \uc218\ub97c \uc9c1\uc0ac\uac01\ud615 \ubaa8\uc591\uc73c\ub85c \ubc30\uc5f4\ud55c \ub4a4 \uad04\ud638\ub85c \ubb36\uc5b4 \ub098\ud0c0\ub0b8 \uac83\uc774\ub2e4. \uc608\ucee8\ub300 \\(2\\)\uac1c\uc758 \ud589\uacfc \\(2\\)\uac1c\uc758 \uc5f4\uc744 \uac00\uc9c4 \uc2e4\ud589\ub82c, \uc989 \\(2\\times 2\\) \uc2e4\ud589\ub82c(real matrix)\uc740 \ub2e4\uc74c\uacfc \uac19\uc774 \ub098\ud0c0\ub0b8\ub2e4.
\n\\[\\left[
\n\\begin{array}{cc}
\na_{11} & a_{12} \\\\
\na_{21} & a_{22}
\n\\end{array}
\n\\right].\\]
\n\uc5ec\uae30\uc11c \\(a_{ij}\\)\ub294 \\(i\\)\uc9f8 \ud589 \\(j\\)\uc9f8 \uc5f4\uc758 \uc131\ubd84(component)\uc774\uba70, \uadf8 \uac12\uc740 \uc2e4\uc218\uc774\ub2e4.<\/p>\n

\\(A\\)\uc640 \\(B\\)\uac00 \\(2\\times 2\\) \ud589\ub82c\uc774\uace0
\n\\[A = \\left[
\n\\begin{array}{cc}
\na_{11} & a_{12} \\\\
\na_{21} & a_{22}
\n\\end{array}
\n\\right] ,\\quad
\nB = \\left[
\n\\begin{array}{cc}
\nb_{11} & b_{12} \\\\
\nb_{21} & b_{22}
\n\\end{array}
\n\\right]\\]
\n\ub77c\uace0 \ud558\uc790. \uc774\ub54c \\(A=B\\)\ub294 \ubaa8\ub4e0 \\(i,\\) \\(j\\)\uc5d0 \ub300\ud558\uc5ec \\(a_{ij} = b_{ij}\\)\ub97c \uc758\ubbf8\ud558\ub294 \uac83\uc73c\ub85c \uc57d\uc18d\ud55c\ub2e4.<\/p>\n

\\(k\\)\uac00 \uc2e4\uc218\uc77c \ub54c \\(k\\)\uc640 \ud589\ub82c \\(A\\)\uc758 \uc2a4\uce7c\ub77c\uacf1<\/span>(scalar product)\uc744 \ub2e4\uc74c\uacfc \uac19\uc774 \uc815\uc758\ud55c\ub2e4.
\n\\[kA = \\left[
\n\\begin{array}{cc}
\nka_{11} & ka_{12} \\\\
\nka_{21} & ka_{22}
\n\\end{array}
\n\\right].\\]
\n\uadf8\ub9ac\uace0 \ub450 \ud589\ub82c\uc758 \ud569\uc744 \ub2e4\uc74c\uacfc \uac19\uc774 \uc815\uc758\ud55c\ub2e4.
\n\\[A+B = \\left[
\n\\begin{array}{cc}
\na_{11} + b_{11} \\,&\\, a_{12} + b_{12} \\\\
\na_{21} + b_{21} \\,&\\, a_{22} + b_{22}
\n\\end{array}
\n\\right].\\]
\n\ud589\ub82c\uc758 \uacf1\uc758 \uc815\uc758\ub294 \ub2e4\uc18c \ubcf5\uc7a1\ud558\ub2e4. \ub450 \ud589\ub82c \\(AB\\)\uc758 \uacf1\uc758 \\(ij\\)-\uc131\ubd84\uc740 \\(A\\)\uc758 \\(i\\)\uc9f8 \ud589\uacfc \\(B\\)\uc758 \\(j\\)\uc9f8 \uc5f4\uc758 \uc810\uacf1(\ubca1\ud130\uc758 \ub0b4\uc801)\uc73c\ub85c \uc815\uc758\ub41c\ub2e4. \uc989
\n\\[AB = \\left[
\n\\begin{array}{cc}
\na_{11} b_{11} + a_{12} b_{21} \\,&\\, a_{11} b_{12} + a_{12} b_{22} \\\\
\na_{21} b_{11} + a_{22} b_{21} \\,&\\, a_{21} b_{12} + a_{22} b_{22}
\n\\end{array}
\n\\right].\\]<\/p>\n

\ud589\ub82c \\(A\\)\uc758 \ud589\uacfc \uc5f4\uc744 \ubc14\uafbc \ud589\ub82c
\n\\[A^{\\rm{T}}
\n= \\left[
\n\\begin{array}{cc}
\nka_{11} & ka_{21} \\\\
\nka_{12} & ka_{22}
\n\\end{array}
\n\\right]\\]
\n\ub97c \\(A\\)\uc758 \uc804\uce58\ud589\ub82c<\/span>(transpose)\uc774\ub77c\uace0 \ubd80\ub978\ub2e4.<\/p>\n

\\(A,\\) \\(B,\\) \\(C\\)\uac00 \\(2\\times 2\\) \ud589\ub82c\uc77c \ub54c \ub2e4\uc74c\uc774 \uc131\ub9bd\ud55c\ub2e4.<\/p>\n