{"id":7625,"date":"2007-08-16T06:53:00","date_gmt":"2007-08-16T06:53:00","guid":{"rendered":"http:\/\/melotopia.net\/b\/?p=7625"},"modified":"2007-08-16T06:53:00","modified_gmt":"2007-08-16T06:53:00","slug":"%ed%91%b8%eb%a6%ac%ec%97%90-%eb%b3%80%ed%99%98fourier-transformation-2","status":"publish","type":"post","link":"http:\/\/melotopia.net\/b\/?p=7625","title":{"rendered":"\ud478\ub9ac\uc5d0 \ubcc0\ud658(Fourier Transformation) #2"},"content":{"rendered":"
\n 0.\ubca1\ud130(Vector)
\n
\n \ubca1\ud130\ub294 \uacf5\uac04\uc5d0\uc11c \uc5b4\ub5a4 \uc810\ub4e4\uc744 \uac16\uace0 \ub367\uc148\uc744 \ud558\uace0 \uc2f6\uc744 \ub54c \uc4f0\ub294 \uac1c\ub150\uc774\ub2e4. \uacf5\uac04\uc740 \uc810\uc744 \ub9ce\uc774 \ubaa8\uc544\ub454 \uac83\uc778\ub370, \uc810\ub9c8\ub2e4 \uc774\ub984\uc774 \uc788\ub2e4. \uc810\ub4e4\uc774 \uac16\uace0 \uc788\ub294 \uc774\ub984\uc744 \uc88c\ud45c\ub77c\uace0 \ubd80\ub974\ub294\ub370, \ud754\ud788 \uc22b\uc790\ub97c \ub9ce\uc774 \uc4f4\ub2e4. \uad73\uc774 \uc22b\uc790\ub97c \uc4f0\uc9c0 \uc54a\uc544\ub3c4 \ub418\uc9c0\ub9cc \ubb34\ud55c\ud788 \ub9ce\uc740 \ub300\uc0c1\uc744 \ud45c\ud604\ud558\ub294\ub370\ub294 \uc22b\uc790\ub97c \uc0ac\uc6a9\ud558\ub294 \uac83\uc774 \uc544\ubb34\ub798\ub3c4 \ud3b8\ub9ac\ud558\ub2e4. \ub9e4\ubc88 \ud2b9\uc815 \uc22b\uc790\ub97c \ub193\uace0 \uc598\uae30\ub97c \ud560 \uc218 \uc5c6\uc73c\ubbc0\ub85c \uc218\ud559\uc790\ub4e4\uc740 \uc544\ubb34 \uc22b\uc790\ub098 \uac16\ub2e4 \ub194\ub3c4 \ub41c\ub2e4\ub294 \ub73b\uc5d0\uc11c $$a,b,c…x,y,z, \\alpha,\\beta…$$\ub4f1\uc758 \uc774\uc0c1\ud55c \ubb38\uc790\ub4e4\uc744 \uc22b\uc790 \ub300\uc2e0 \uc801\uc5b4\ub454\ub2e4. \uc544\ubb34\ud2bc, \uacf5\uac04\uc5d0 \uc788\ub294 \uc810\ub4e4\uc774 \ubca1\ud130\uac00 \ub418\uba74 \uadf8 \uacf5\uac04\uc740 \ubca1\ud130 \uacf5\uac04(Vector Space)\uc774\ub77c\uace0 \ubd80\ub978\ub2e4. \uc7a0\uae50. \uadf8 \uc804\uc5d0 \ubca1\ud130\uac00 \ubb54\uc9c0 \uc54c\uc544\uc57c \ud558\ub294\uac83 \uc544\ub2cc\uac00.
\n
\n \uc218\ud559\uc801\uc73c\ub85c \ubca1\ud130\ub294 \ub2e4\uc74c\uacfc \uac19\uc774 \uc815\uc758\ub41c\ub2e4.(\uc880 \ub354 \uc5c4\ubc00\ud55c \uc815\uc758\ub294 \uc120\ud615\ub300\uc218\ud559 \ucc45\uc744 \ucc38\uace0\ud558\uae30 \ubc14\ub780\ub2e4)
\n
\n \uc5b4\ub5a4 \uacf5\uac04\uc744 V\ub77c\uace0 \ud558\uace0, \uadf8 \uc548\uc5d0 x, y, z\uac00 \uc788\ub2e4\uace0 \ud558\uba74,
\n <\/p>\n
    \n
  1. \n x+y\uac00 V\uc548\uc5d0 \uc788\ub2e4\n <\/li>\n
  2. \n x+y = y+x (\uad50\ud658\ubc95\uce59)\n <\/li>\n
  3. \n x+(y+z) = (x+y)+z (\uacb0\ud569\ubc95\uce59)\n <\/li>\n
  4. \n V\uc548\uc5d0 0\uc774 \uc788\ub2e4. 0\uc740 V\uc548\uc5d0\uc11c x+0=0+x=x\uc778 \ud2b9\uc9d5\uc744 \uac00\uc838\uc57c \ud55c\ub2e4. ()\n <\/li>\n
  5. \n V\uc548\uc5d0 \uc788\ub294 \uc544\ubb34 x\uc5d0 \ub300\ud558\uc5ec, x+(-x) = 0\uc774 \ub418\ub3c4\ub85d \ud558\ub294 “-x”\ub77c\ub294 \uac83\uc774 \uc874\uc7ac\ud55c\ub2e4. (\uc5ed\uc6d0\uc774 \uc788\ub2e4)
    \n
    \n \uc5ec\uae30\uae4c\uc9c0 \ub9cc\uc871\ud558\uba74 V\ub294 Abelian Group\uc774 \ub41c\ub2e4. (\ub367\uc148\uc774 \uc798\ub41c\ub2e4\ub294 \ub73b)
    \n
    \n \ub610\ud55c \uc544\ubb34 \ubca1\ud130 x, y\uc640 \uadf8\ub0e5 \uc22b\uc790 a, b\uc5d0 \ub300\ud574\uc11c\n <\/li>\n
  6. \n ax\uac00 V\uc548\uc5d0 \uc788\ub2e4\n <\/li>\n
  7. \n (a+b)x=ax+bx\n <\/li>\n
  8. \n a(x+y)=ax+ay\n <\/li>\n
  9. \n (ab)x=a(bx)\n <\/li>\n
  10. \n 1x=x (1\uc740 \uacf1\uc148\uc5d0 \ub300\ud55c \ud56d\ub4f1\uc6d0)\n <\/li>\n<\/ol>\n

    \uc5ec\uae30\uae4c\uc9c0\ub97c \ub9cc\uc871\ud558\uba74 V\ub294 Scalar Multiplication\uc774 \uc798\ub41c\ub2e4.
    \n
    \n \uc704\uc758 \uc5f4\uac00\uc9c0 \uc870\uac74\uc744 \ubaa8\ub450 \ub9cc\uc871\ud558\uba74 V\uac00 \ubca1\ud130 \uacf5\uac04\uc774 \ub41c\ub2e4. \uc694\uc57d\ud558\uc790\uba74,
    \n
    \n \ub367\uc148 \uc798\ub418\uace0 \uae38\uc774\ub97c \ubc14\uafc0 \uc218 \uc788\uc73c\uba74 \ubca1\ud130 \uacf5\uac04\uc774\ub77c\ub294 \ub73b\uc774\ub2e4.
    \n <\/span>
    \n
    \n \uc774\uac83\uc740 \uc6b0\ub9ac\uac00 \uae38\ucc3e\uae30 \ud560 \ub54c \ub3d9\ucabd\uc73c\ub85c \uac00\uace0 \ub0a8\ucabd\uc73c\ub85c \uac00\ub4e0, \ub0a8\ucabd\uc73c\ub85c \uac00\uace0 \ub3d9\ucabd\uc73c\ub85c \uac00\ub4e0 \uc0c1\uad00 \uc5c6\ub2e4\ub294 \uac83\uc744 \uc758\ubbf8\ud55c\ub2e4.
    \n
    \n \ucc38\uace0\ub85c $$f:\\mathbb{R}^n\\rightarrow\\mathbb{R}^m$$\uc778 \ud568\uc218\ub97c \ubaa8\ub450 \ubaa8\uc544\ub454 \uacf5\uac04\ub3c4 \ubca1\ud130 \uacf5\uac04\uc774\ub2e4. \uc774\uac83\uc740 \uc544\uc8fc \uc911\uc694\ud55c \uc598\uae30\uc774\ub2e4.<\/p>\n

    1.\uc0ac\uc601(Projection)
    \n
    \n \ubca1\ud130\uc5d0 \ub300\ud574\uc11c \uacf5\ubd80\ud558\ub2e4\ubcf4\uba74 “\ub0b4\uc801(inner product)”\uc774\ub77c\ub294 \uac1c\ub150\uc774 \ub4f1\uc7a5\ud55c\ub2e4. \uc774\uac83\uc740 \uadf8\ub0e5 \ub450 \ubca1\ud130 \uc0ac\uc774\uc5d0 \uc5b4\ub5a4 \uc5f0\uad00\uc131\uc774 \uc788\ub294\uc9c0 \uc54c\uc544\ubcf4\uae30 \uc704\ud574\uc11c \ub4f1\uc7a5\ud55c \uac83\uc778\ub370, \uacc4\uc0b0\uc740 \ub2e8\uc21c\ud558\ub2e4.
    \n
    \n $$\\vec{a} = (a_1, a_2, a_3)$$ \uc774\uace0 $$\\vec{b} = (b_1, b_2, b_3)$$ \ub77c\uace0 \ud558\uba74, \uc774\uc81c \ub450 \ubca1\ud130\uc5d0\uc11c \uc22b\uc790 \ud55c\uac1c\ub97c \ub9cc\ub4e4\uc5b4 \ub0bc \uc218 \uc788\ub2e4.
    \n
    \n $$\\vec{a} \\cdot \\vec{b} = a_1b_1 + a_2b_2 + a_3b_3$$
    \n
    \n \uc774\ub7f0\uc2dd\uc73c\ub85c \uac01\uac01\uc758 \uc131\ubd84 \uc21c\uc11c\ub300\ub85c \uc9dd\uc744 \uc9c0\uc5b4\uc11c \ub354\ud55c \uac83\uc744 \uadf8\ub0e5 \ub0b4\uc801\uc774\ub77c\uace0 \ubd80\ub978\ub2e4. \uc800 \uac00\uc6b4\ub370\uc758 \uc810 \ucc0d\uc740\uac74 \uadf8\ub0e5 \ub450 \ubca1\ud130 \uc0ac\uc774\uc758 \uc5f0\uad00\uc131\uc774\ub77c\ub294 \ub73b\uc744 \uac16\uace0 \uc788\ub2e4\uace0 \ubcf4\uba74 \ub41c\ub2e4.
    \n
    \n \uc218\ud559\uc801\uc73c\ub85c \ub0b4\uc801\uc740 \ub2e4\uc74c\uacfc \uac19\uc774 \uc815\uc758\ub41c\ub2e4. \uadf8\ub0e5 a\uc640 b\uac00 \ubca1\ud130 \uacf5\uac04\uc5d0 \uc788\ub294 \ub450 \ubca1\ud130\ub77c\uace0 \ud558\uba74 x, y\uac00 \ubca1\ud130\uc774\uace0 k\uac00 \uadf8\ub0e5 \uc22b\uc790\uc77c \ub54c,
    \n
    \n $$=$$
    \n
    \n $$=+$$
    \n
    \n $$=k$$
    \n
    \n $$\\le 0$$
    \n
    \n \ub0b4\uc801\uc774 \uc798 \uc815\uc758\ub418\ub294 \uacf5\uac04\uc744 \ub0b4\uc801 \uacf5\uac04(Inner product space)\ub77c\uace0 \ubd80\ub978\ub2e4.
    \n
    \n \ub0b4\uc801\uc774 \uc798 \uc774\ud574\uac00 \uc548\ub41c\ub2e4\uba74,
    \n
    \n \ud55c \ubca1\ud130\uc5d0\uc11c \ub2e4\ub978 \ubca1\ud130\ub85c \ube5b\uc744 \uc408\uc744 \ub54c \ubcf4\uc774\ub294 \uadf8\ub9bc\uc790\uc758 \uae38\uc774
    \n <\/span>
    \n \ub97c \ub0b4\uc801\uc774\ub77c\ub294 \uc22b\uc790\ub85c \uc0dd\uac01\ud558\uba74 \ub41c\ub2e4.<\/p>\n

    2.\ubca1\ud130 \uacf5\uac04\uc758 \uae30\uc800
    \n
    \n basis : \uae30\uc800
    \n
    \n 3\ucc28\uc6d0 \uacf5\uac04\uc5d0\ub294 \ubc29\ud5a5\uc774 3\uac1c \uc788\ub2e4. \ubb3c\ub860 n\ucc28\uc6d0 \uacf5\uac04\uc5d0\ub294 \ubc29\ud5a5\uc774 n\uac1c \uc788\ub2e4. \uc774\ub807\uac8c \ub9d0\ud560 \uc218 \uc788\ub294 \uc774\uc720\ub294 \uc801\ub2f9\ud55c \ubca1\ud130 3\uac1c\ub9cc \uc788\uc73c\uba74 3\ucc28\uc6d0 \uacf5\uac04\uc5d0 \uc788\ub294 \ubaa8\ub4e0 \ubca1\ud130\ub97c \uadf8 3\uac1c\uc758 1\ucc28 \uacb0\ud569\uc73c\ub85c \ud45c\ud604\ud560 \uc218 \uc788\uae30 \ub54c\ubb38\uc774\ub2e4.
    \n
    \n 1\ucc28 \uacb0\ud569\uc774\ub780 \ub2e4\uc74c\uacfc \uac19\ub2e4. a\uc640 b\uac00 \uc22b\uc790\uc774\uace0, x\uc640 y\uac00 \ubca1\ud130\uc774\uba74 ax+by\ub294 \ub2f9\uc5f0\ud788 \ubca1\ud130 \uacf5\uac04 \uc548\uc5d0 \uc788\ub294 \ub2e4\ub978 \ubca1\ud130\uc778\ub370, ax+by\ub294 x\uc640 y\uc758 1\ucc28 \uacb0\ud569\uc73c\ub85c \ud45c\ud604\ub41c \ubca1\ud130\uc774\ub2e4.<\/p>\n

    \uc55e\uc11c \uc608\ub97c \ub4e4\uc5c8\ub4ef\uc774 \ud568\uc218\ub97c \ubaa8\uc544\ub454 \uacf5\uac04\ub3c4 \ubca1\ud130 \uacf5\uac04\uc774\ub2e4. \uc608\ub97c\ub4e4\uc5b4 sin(x)\uc640 cos(x)\uac00 \uc2e4\uc218\uc5d0\uc11c \uc2e4\uc218\ub85c \uac00\ub294 \ud568\uc218\ub77c\uba74, sin(x)+4cos(x)\ub3c4 \uc2e4\uc218\uc5d0\uc11c \uc2e4\uc218\ub85c \uac00\ub294 \ud568\uc218\uc774\ubbc0\ub85c, \ubca1\ud130\ub85c\uc11c \uc798 \ub354\ud574\uc9c4 \uac83\uc774\ub2e4. \uadf8\ub7f0\ub370 \uc774\ub7f0 \uacf5\uac04\uc5d0\uc11c \ubc29\ud5a5\uc744 \ucc3e\ub294\ub2e4\ub294 \uac83\uc740 \uc5b4\ub5a4 \uac83\uc77c\uae4c? \ud55c\uac00\uc9c0 \uc6b0\ub9ac\uac00 \uc0dd\uac01\ud574\ubcfc \uc218 \uc788\ub294 \ud78c\ud2b8\ub294 3\ucc28\uc6d0 \uacf5\uac04\uc5d0\uc11c \ubc29\ud5a5 3\uac1c\ub294 \uc11c\ub85c \ub3c5\ub9bd\uc801\uc774\ub77c\ub294 \uac83\uc774\ub2e4. \uc608\ub97c\ub4e4\uc5b4, \ub0a8\ucabd \ubc29\ud5a5\uc5d0 \uc788\ub294 \uc9d1\uc740 \ub54c\ub824 \uc8fd\uc5ec\ub3c4 \ub3d9\ucabd\uc73c\ub85c \uac00\uc11c \ucc3e\uc744 \uc218 \uc5c6\ub2e4. \ubca1\ud130\uc5d0\uc11c \uc774\ub7f0 \uac83\uc744 \uc11c\ub85c \ub3c5\ub9bd\uc774\ub77c\uace0 \ub9d0\ud558\uba70, x, y\uac00 \ubca1\ud130\uc774\uace0 a\uac00 \uc22b\uc790\uc77c \ub54c y=ax\uc778 a\uac00 \ud55c\uac1c\ub3c4 \uc5c6\ub294 \uac83\uc744 \ub9d0\ud55c\ub2e4.
    \n
    \n \uac00\ub839, \ub0a8\ucabd 2\uce35 \uc9d1\uc740 “\ub0a8\ucabd” \ubca1\ud130\uc640 “\uc704” \ubca1\ud130 \ub450\uac1c\ub97c \uc801\ub2f9\ud788 \uc870\ud569\ud558\uc5ec \ub9cc\ub4e4 \uc218 \uc788\ub2e4. \uadf8\ub7ec\ub098 \ub3d9\ucabd\uc9d1\uc740 \ub0a8\ucabd \ubca1\ud130\uc640 \uc704\ucabd \ubca1\ud130\ub85c\ub294 \uc808\ub300 \ub3c4\ucc29\ud560 \uc218\uac00 \uc5c6\ub2e4. \ub9cc\uc57d \ub0a8\ucabd, \ub3d9\ucabd, \uc704\ucabd \ubca1\ud130\ub97c \uac16\uace0 \uc788\uc73c\uba74 \uc6b0\ub9ac\ub294 \uc5b4\ub290 \uc9d1\uc774\ub098 \uac08 \uc218 \uc788\ub2e4. \ub0a8\ucabd\uc73c\ub85c 100\ubbf8\ud130, \ub3d9\ucabd \ubc18\ub300(\uc11c\ucabd)\ub85c 50\ubbf8\ud130, \uc704\ub85c 4\uce35 \ub4f1\ub4f1. \uc774\ub807\uac8c \ub418\ub294 \uacbd\uc6b0 3\ucc28\uc6d0 \uacf5\uac04\uc740 3\uac1c\uc758 \ubca1\ud130\ub85c \uc644\uc804\ud788 \ud45c\ud604\ub41c\ub2e4\uace0 \ub9d0\ud55c\ub2e4.<\/p>\n

    \ud568\uc218\ub4e4\uc5d0\uc11c\ub3c4 \uc774\ub7f0 \uad00\uacc4\ub97c \ucc3e\uc744 \uc218 \uc788\ub294\ub370, sin(x)\uc5d0 \uc5b4\ub5a4 \uc22b\uc790\ub97c \uacf1\ud558\ub354\ub77c\ub3c4 cos(x)\uac00 \ub098\uc624\uc9c0\ub294 \uc54a\ub294\ub2e4. \ub530\ub77c\uc11c \uc774 \ub450 \ud568\uc218\ub294 \uc11c\ub85c \ub3c5\ub9bd\uc774\ub2e4. \uadf8\ub807\ub2e4\uba74, \ud568\uc218\ub85c \uc774\ub8e8\uc5b4\uc9c4 \ubca1\ud130 \uacf5\uac04\uc740 \ubc29\ud5a5\uc774 \uba87\uac1c\uc77c\uae4c? \uc5b4\ub824\uc6b4 \uc598\uae30\uc9c0\ub9cc, \uc77c\ubc18\uc801\uc73c\ub85c \ubb34\ud55c\ud788 \ub9ce\uc740 \ubc29\ud5a5\uc744 \uac00\uc9c8 \uc218 \uc788\ub2e4. \uac10\ud788 \uc11c\ub108\uac1c \uc815\ub3c4\uc758 \ubc29\ud5a5\uc73c\ub85c \uc0c1\uc0c1\ud574\ubcfc \ubc94\uc8fc\uac00 \uc544\ub2cc \uac83\uc774\ub2e4. \uadf8\ub798\uc11c \uc218\ud559\uc790\ub4e4\uc740 \uc774\ub7ec\ud55c \ubc29\ud5a5\uc5d0 \ub300\ud574 \uc0dd\uac01\ud558\ub2e4\uac00 \uaddc\uce59\uc744 \ucc3e\uac8c \ub418\uc5c8\ub2e4.
    \n
    \n \ubb34\ud55c\ud788 \ubbf8\ubd84 \uac00\ub2a5\ud55c \ub9e4\ub044\ub7ec\uc6b4 \ud568\uc218\ub4e4\uc744 \ud45c\ud604\ud558\ub294\ub370 \uac00\uc7a5 \ud3b8\ud55c \uac83\uc740 \ud14c\uc77c\ub7ec \uae09\uc218\uc774\ub2e4. \uc5ec\uae30\uc11c\ub294 $$x^n$$\ud615\ud0dc\uc758 \ud568\uc218\ub4e4\uc774 \ubc29\ud5a5\uc744 \ud45c\ud604\ud558\ub294 \uae30\ubcf8\uc801\uc778 \ud568\uc218\uac00 \ub41c\ub2e4. \uc774\uac83\ub4e4\uc740 \ub9c8\uce58 (1,0)\uc774\ub098 (0,1)\ucc98\ub7fc \ud568\uc218 \uacf5\uac04\uc744 \ud45c\ud604\ud574\uc8fc\ub294 \uae30\ubcf8 \ud568\uc218\uac00 \ub41c\ub2e4. \ud558\uc9c0\ub9cc \uc774\ub7f0 \ud568\uc218\ub4e4\uc740 \ubb38\uc81c\uac00 \uc788\ub294\ub370, \uc11c\ub85c \uc9c1\uac01\uc744 \uc774\ub8e8\uc9c0 \uc54a\ub294\ub2e4\ub294 \uac83\uc774\ub2e4. \uc5e5? \uc9c1\uac01? \ub208\uc5d0 \ubd48\uc9c0\ub3c4 \uc54a\ub294 \ud568\uc218 \uacf5\uac04\uc5d0\uc11c \uc6ec \uc9c1\uac01?<\/p>\n

    sin(x)\uc640 sin(2x)\ub294 \uc11c\ub85c \ub2e4\ub978 \ubc29\ud5a5\uc744 \uac00\ub9ac\ud0a4\ub294 \ud568\uc218\ub2e4. \uc774\uac83\uc740 \uc55e\uc11c \uc598\uae30\ud55c\ub300\ub85c \uc5b4\ub5a4 \uc22b\uc790\ub97c \uacf1\ud558\ub354\ub77c\ub3c4 \uc5b4\ub290 \ud558\ub098\ub97c \ub2e4\ub978 \ud558\ub098\ub85c \ubc14\uafc0 \uc218 \uc5c6\ub2e4\ub294 \ub73b\uc774\ub2e4. \uc218\ud559\uc790\ub4e4\uc740 \uc774 \ub450\uac00\uc9c0 \ubca1\ud130 \uc0ac\uc774\uc758 \uac01\ub3c4\ub97c \uc7ac\ub294 \ubc29\ubc95\uc744 \uace0\uc2ec\ud558\ub2e4\uac00 \uc774 \ud568\uc218\ub77c\ub294 \uac83\uc774 \ubb34\uc5c7\uc778\uc9c0 \uae68\ub2ec\uc558\ub2e4. \ud568\uc218\ub294 \uc218\uc5f4\uc758 \ud655\uc7a5\ud310\uc778\ub370, \uc218\uc5f4\uc740 \ubca1\ud130\uc778 \uac83\uc774\ub2e4. \uc989 \ubca1\ud130\ub97c (1,2,4)\ucc98\ub7fc \uc720\ud55c\ud55c \uac83\ub9cc\uc774 \uc544\ub2c8\ub77c (3,4,1,4,5,2,7,7,8,…)\ub4f1\uc73c\ub85c \ubb34\ud55c \ucc28\uc6d0\uc5d0\uc11c\ub294 \ubb34\ud55c\ud788 \uae38\uac8c \uc801\uc744 \uc218 \uc788\uc73c\ubbc0\ub85c \uc800 \uac01\uac01\uc740 \uc218\uc5f4\uc774\ub2e4. \uadf8\ub7f0\ub370, \uc218\uc5f4\uc740 \uccab\ubc88\uc9f8, \ub450\ubc88\uc9f8 \ub4f1\uc73c\ub85c \uc21c\uc11c\ub97c \ub9e4\uaca8\uc11c \uadf8 \uc21c\uc11c\uc5d0 \ud574\ub2f9\ud558\ub294 \uc22b\uc790\ub97c \uc815\ud574\uc900 \uac83\uc774\ub2e4. \uadf8\ub9ac\uace0 \ud568\uc218\ub294, \uc870\uae08 \ub2e8\uc21c\ud788 \ub9d0\ud558\uc790\uba74 \uadf8 \uccab\ubc88\uc9f8, \ub450\ubc88\uc9f8\uc758 \uc0ac\uc774\uc0ac\uc774\uc5d0 \ubaa8\ub4e0 \uc22b\uc790\ub97c \ub2e4 \ub123\uc5b4\uc900 \uac83\uc774\ub77c\uace0 \ubcf4\uba74 \ub41c\ub2e4. \ub530\ub77c\uc11c, \ubca1\ud130\uc758 \ub0b4\uc801\uc744 \ucc3e\uc744 \ub54c \uccab\ubc88\uc9f8 \ub07c\ub9ac \uacf1\ud558\uace0, \ub450\ubc88\uc9f8 \ub07c\ub9ac \uacf1\ud574\uc11c \uc9dd\ub9de\ucdb0\uc11c \uacf1\ud55c\uac78 \ubaa8\ub450 \ub354\ud588\uc73c\ubbc0\ub85c \ud568\uc218\ub3c4 \ub9c8\ucc2c\uac00\uc9c0 \ubc29\ubc95\uc744 \uc774\uc6a9\ud558\uba74 \ub41c\ub2e4. \uadf8\ub9ac\ud558\uc5ec \ub450 \ud568\uc218 f(x)\uc640 g(x)\uc0ac\uc774\uc758 \ub0b4\uc801\uc740, x\ubc88\uc9f8 \uc9dd\uc744 \ub9de\ucdb0\uc11c \uacf1\ud55c f(x)g(x)\ub97c \ubaa8\ub450 \ub354\ud55c $$\\int dx f(x)g(x)$$ \uac00 \ub418\ub294 \uac83\uc774\ub2e4. \uc774 \ub0b4\uc6a9\uc774 \uc5b4\ub835\ub2e4\uba74, \uc544\ubb34\ud2bc
    \n
    \n \ub450 \ud568\uc218 \uc0ac\uc774\uc758 \uac01\ub3c4\ub97c \uc7b4 \uc218 \uc788\ub2e4
    \n <\/span>
    \n \ub294 \uac83\ub9cc \uc54c\uc544\ub450\uc790.
    \n
    \n \uc5b4\ub5a4 \ub450 \ubca1\ud130\ub97c \ub0b4\uc801\uc2dc\ud0a4\uba74 \ub2e4\uc74c\uc758 \uad00\uacc4\uac00 \uc131\ub9bd\ud55c\ub2e4.
    \n
    \n $$\\vec{A}\\cdot\\vec{B} = \\mid A\\mid \\mid B \\mid \\cos\\theta$$
    \n
    \n \ub530\ub77c\uc11c \uac01\ub3c4 $$\\theta$$\ub97c \uc54c\uc544\ub0bc \uc218\uac00 \uc788\uc73c\uba70, \ub9cc\uc57d \ub0b4\uc801\uc774 0\uc774\uba74 \ub450 \ubca1\ud130\ub294 \uc9c1\uac01\uc744 \uc774\ub8ec\ub2e4\uace0 \ubd80\ub978\ub2e4. \ub2e4\ub978\uac74 \ubab0\ub77c\ub3c4 \uc9c1\uac01\uc778\uc9c0 \uc544\ub2cc\uc9c0\ub294 \ud655\uc2e4\ud788 \uc54c \uc218 \uc788\ub2e4.<\/p>\n

    \uc9c1\uac01\uc778 \ub450 \ubca1\ud130\ub294 \uc11c\ub85c \ub07c\uc5b4\ub4e4\uc5b4\uac00\ub294 \uc131\ubd84\uc774 \uc5c6\ub2e4. \uc989, A\uc5d0\ub2e4\uac00 B\ub97c \ubc31\ub0a0 \ube44\ucdb0\ubd10\uc57c \uadf8\ub9bc\uc790\uac00 \uc0dd\uae30\uc9c0 \uc54a\ub294\ub2e4\ub294 \ub73b\uc774\ub2e4. \uc27d\uac8c \ub9d0\ud574\uc11c, \ub0a8\ucabd\uc73c\ub85c \ub2ec\ub824\uac00\uba74 \uc544\ubb34\ub9ac \ub2ec\ub824\uac00\ub3c4 \ub3d9\ucabd\uc73c\ub85c\ub294 \ub2e8 \ud55c\ubc1c\uc9dd\ub3c4 \uc6c0\uc9c1\uc5ec\uc9c0\uc9c0 \uc54a\ub294\ub2e4\ub294 \ub73b\uc774\ub2e4.<\/p>\n

    \ud568\uc218\uacf5\uac04\uc5d0\uc11c\ub294 \uc774\ub7ec\ud55c \uc9c1\uad50\ud558\ub294 \uae30\uc800 \ubca1\ud130\ub4e4\uc744 \ucc3e\uc544\ub0b4\ub294 \uac83\uc774 \uc544\uc8fc \uc911\uc694\ud55c\ub370, \uc218\ud559\uc790\ub4e4\uc774 \uc5ec\ub7ec\uac00\uc9c0\ub97c \ucc3e\uc544\ub0b4\uc11c \uc790\uae30 \uc774\ub984\uc744 \ubd99\uc5ec\ub1a8\ub2e4. Legendre, Laguerre, Hermit, Hankel…
    \n
    \n \uadf8\ub9ac\uace0 \uc6b0\ub9ac\uc758 \uc601\uc6c5 Fourier\ub3c4 \uc9c1\uad50\ud558\ub294 \uae30\uc800 \ubca1\ud130\ub4e4\uc744 \ucc3e\uc558\ub294\ub370, \uc548\ud0c0\uae5d\uac8c\ub3c4 Fourier\uac00 \ucc3e\uc544\ub0b8 \uac83\uc740 \uc0bc\uac01\ud568\uc218\ub4e4\uc774\ub77c \uadf8\ub0e5 \uc0bc\uac01\ud568\uc218\ub77c\uace0 \ubd80\ub974\uac8c \ub418\uc5c8\ub2e4. \ub108\ubb34 \uc624\ub798\uc804\ubd80\ud130 \uc368 \uc624\ub358\uac70\ub77c \uc774\ub984\uc744 \ubc14\uafc0 \uc218\uac00 \uc5c6\uc5c8\ub2e4. sin \ud568\uc218\ub97c Fourier 1\ubc88 \ud568\uc218\ub77c\uace0 \ubd80\ub974\uba74 \uc5b4\uc0c9\ud558\uc796\uc544.<\/p>\n

    sin(ax)*sin(bx)\ub77c\ub294 \ud568\uc218\ub97c \ubaa8\ub4e0 \uad6c\uac04\uc5d0\uc11c \uc801\ubd84\ud558\uba74, a\uc640 b\uac00 \uac19\uc9c0 \uc54a\uc73c\uba74 \ubc18\ub4dc\uc2dc 0\uc774 \ub41c\ub2e4. cos\ub07c\ub9ac \uacf1\ud55c \uac83\ub3c4 \ub9c8\ucc2c\uac00\uc9c0\uc774\ub2e4. sin\uacfc cos\uc744 \uacf1\ud55c \uac83\uc740 a\uc640 b\uc5d0 \uc0c1\uad00 \uc5c6\uc774 \ubc18\ub4dc\uc2dc 0\uc774\ub2e4. \ub530\ub77c\uc11c \uc0bc\uac01\ud568\uc218\ub294 \ubaa8\ub4e0 \ud568\uc218\ub97c \ud45c\ud604\ud560 \uc218 \uc788\ub294 \uc9c1\uad50 \uae30\uc800\uac00 \ub41c\ub2e4!<\/p>\n

    \ud478\ub9ac\uc5d0\uc758 \uc815\ub9ac : \ubaa8\ub4e0 \uc5f0\uc18d\ud568\uc218\ub294 \uc0bc\uac01\ud568\uc218\uc758 \uc120\ud615 \uacb0\ud569\uc73c\ub85c \ud45c\ud604\ud560 \uc218 \uc788\ub2e4.<\/p>\n

    \ud478\ub9ac\uc5d0 \ubcc0\ud658 : \uc8fc\uc5b4\uc9c4 \ud568\uc218\ub97c \uc0bc\uac01\ud568\uc218\uc758 \uc120\ud615 \uacb0\ud569\uc73c\ub85c \ud45c\ud604\ud560 \ub54c, \uadf8 \uacb0\ud569\uc744 \ud45c\ud604\ud558\ub294 \uacc4\uc218\ub9cc \uace8\ub77c\ub0b4\uc11c \uc0c8\ub85c\uc6b4 \ud568\uc218\ub85c \uac04\uc8fc\ud55c\ub2e4. \uc774\uac83\uc744 \ud478\ub9ac\uc5d0 \ubcc0\ud658\uc774\ub77c\uace0 \ubd80\ub978\ub2e4.
    \n
    \n (3\ud3b8\uc5d0\uc11c \uc774\uc5b4\uc9d1\ub2c8\ub2e4…)
    \n <\/p>\n

    \n
    \n
    \n\"\uc2e0\uace0\"
    \n<\/a>\n<\/div>\n<\/div>\n<\/div>\n","protected":false},"excerpt":{"rendered":"

    0.\ubca1\ud130(Vector) \ubca1\ud130\ub294 \uacf5\uac04\uc5d0\uc11c \uc5b4\ub5a4 \uc810\ub4e4\uc744 \uac16\uace0 \ub367\uc148\uc744 \ud558\uace0 \uc2f6\uc744 \ub54c \uc4f0\ub294 \uac1c\ub150\uc774\ub2e4. \uacf5\uac04\uc740 \uc810\uc744 \ub9ce\uc774 \ubaa8\uc544\ub454 \uac83\uc778\ub370, \uc810\ub9c8\ub2e4 \uc774\ub984\uc774 \uc788\ub2e4. \uc810\ub4e4\uc774 \uac16\uace0 \uc788\ub294 \uc774\ub984\uc744 \uc88c\ud45c\ub77c\uace0 \ubd80\ub974\ub294\ub370, \ud754\ud788 \uc22b\uc790\ub97c \ub9ce\uc774 \uc4f4\ub2e4. \uad73\uc774 \uc22b\uc790\ub97c \uc4f0\uc9c0 \uc54a\uc544\ub3c4 \ub418\uc9c0\ub9cc \ubb34\ud55c\ud788 \ub9ce\uc740 \ub300\uc0c1\uc744 \ud45c\ud604\ud558\ub294\ub370\ub294 \uc22b\uc790\ub97c \uc0ac\uc6a9\ud558\ub294 \uac83\uc774 \uc544\ubb34\ub798\ub3c4 \ud3b8\ub9ac\ud558\ub2e4. \ub9e4\ubc88 \ud2b9\uc815 \uc22b\uc790\ub97c \ub193\uace0 \uc598\uae30\ub97c \ud560 \uc218 \uc5c6\uc73c\ubbc0\ub85c \uc218\ud559\uc790\ub4e4\uc740 \uc544\ubb34 \uc22b\uc790\ub098 […]<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"_crdt_document":"","_jetpack_newsletter_access":"","_jetpack_dont_email_post_to_subs":false,"_jetpack_newsletter_tier_id":0,"_jetpack_memberships_contains_paywalled_content":false,"_jetpack_memberships_contains_paid_content":false,"footnotes":""},"categories":[2],"tags":[],"class_list":["post-7625","post","type-post","status-publish","format-standard","hentry","category-academic"],"jetpack_featured_media_url":"","jetpack_sharing_enabled":true,"jetpack_shortlink":"https:\/\/wp.me\/p8o6gA-1YZ","jetpack-related-posts":[],"jetpack_likes_enabled":true,"_links":{"self":[{"href":"http:\/\/melotopia.net\/b\/index.php?rest_route=\/wp\/v2\/posts\/7625","targetHints":{"allow":["GET"]}}],"collection":[{"href":"http:\/\/melotopia.net\/b\/index.php?rest_route=\/wp\/v2\/posts"}],"about":[{"href":"http:\/\/melotopia.net\/b\/index.php?rest_route=\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"http:\/\/melotopia.net\/b\/index.php?rest_route=\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"http:\/\/melotopia.net\/b\/index.php?rest_route=%2Fwp%2Fv2%2Fcomments&post=7625"}],"version-history":[{"count":0,"href":"http:\/\/melotopia.net\/b\/index.php?rest_route=\/wp\/v2\/posts\/7625\/revisions"}],"wp:attachment":[{"href":"http:\/\/melotopia.net\/b\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=7625"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"http:\/\/melotopia.net\/b\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=7625"},{"taxonomy":"post_tag","embeddable":true,"href":"http:\/\/melotopia.net\/b\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=7625"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}