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| In the paper "On the Relative Forms of Quaternions" (CP 3.323), we observe Peirce providing the following sorts of explanation: | | In the paper "On the Relative Forms of Quaternions" (CP 3.323), we observe Peirce providing the following sorts of explanation: |
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− | <pre>
| + | {| align="center" cellpadding="6" width="90%" |
− | | If X, Y, Z denote the three rectangular components of a vector, and W denote | |
− | | numerical unity (or a fourth rectangular component, involving space of four
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− | | dimensions), and (Y:Z) denote the operation of converting the Y component
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− | | of a vector into its Z component, then
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− | | 1 = (W:W) + (X:X) + (Y:Y) + (Z:Z) | + | <p>If <math>X, Y, Z\!</math> denote the three rectangular components of a vector, and <math>W\!</math> denote numerical unity (or a fourth rectangular component, involving space of four dimensions), and <math>(Y:Z)\!</math> denote the operation of converting the <math>Y\!</math> component of a vector into its <math>Z\!</math> component, then</p> |
| + | |- |
| + | | align="center" | |
| + | <math>\begin{matrix} |
| + | 1 & = & (W:W) & + & (X:X) & + & (Y:Y) & + & (Z:Z) |
| + | \\ |
| + | i & = & (X:W) & - & (W:X) & - & (Y:Z) & + & (Z:Y) |
| + | \\ |
| + | j & = & (Y:W) & - & (W:Y) & - & (Z:X) & + & (X:Z) |
| + | \\ |
| + | k & = & (Z:W) & - & (W:Z) & - & (X:Y) & + & (Y:X) |
| + | \end{matrix}</math> |
| + | |- |
| | | | | |
− | | i = (X:W) - (W:X) - (Y:Z) + (Z:Y)
| + | <p>In the language of logic <math>(Y:Z)\!</math> is a relative term whose relate is a <math>Y\!</math> component, and whose correlate is a <math>Z\!</math> component. The law of multiplication is plainly <math>(Y:Z)(Z:X) = (Y:X),\!</math> <math>(Y:Z)(X:W) = 0,\!</math> and the application of these rules to the above values of <math>1, i, j, k\!</math> gives the quaternion relations</p> |
| + | |- |
| + | | align="center" | |
| + | <math>i^2 = j^2 = k^2 = -1, \quad ijk = -1, \quad \text{etc}.</math> |
| + | |- |
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− | | j = (Y:W) - (W:Y) - (Z:X) + (X:Z)
| + | <p>The symbol <math>a(Y:Z)\!</math> denotes the changing of <math>Y\!</math> to <math>Z\!</math> and the multiplication of the result by <math>a.\!</math> If the relatives be arranged in a block</p> |
| + | |- |
| + | | align="center" | |
| + | <math>\begin{matrix} |
| + | W:W && W:X && W:Y && W:Z |
| + | \\ |
| + | X:W && X:X && X:Y && X:Z |
| + | \\ |
| + | Y:W && Y:X && Y:Y && Y:Z |
| + | \\ |
| + | Z:W && Z:X && Z:Y && Z:Z |
| + | \end{matrix}</math> |
| + | |- |
| | | | | |
− | | k = (Z:W) - (W:Z) - (X:Y) + (Y:X) | + | <p>then the quaternion <math>w + xi + yj + zk\!</math> is represented by the matrix of numbers</p> |
| + | |- |
| + | | align="center" | |
| + | <math>\begin{array}{*{7}{r}} |
| + | w && -x && -y && -z |
| + | \\ |
| + | x && w && -z && y |
| + | \\ |
| + | y && z && w && -x |
| + | \\ |
| + | z && -y && x && w |
| + | \end{array}</math> |
| + | |- |
| | | | | |
− | | In the language of logic (Y:Z) is a relative term whose relate is
| + | <p>The multiplication of such matrices follows the same laws as the multiplication of quaternions. The determinant of the matrix = the fourth power of the tensor of the quaternion.</p> |
− | | a Y component, and whose correlate is a Z component. The law of
| + | |
− | | multiplication is plainly (Y:Z)(Z:X) = (Y:X), (Y:Z)(X:W) = 0,
| + | <p>The imaginary <math>x + y \sqrt{-1}</math> may likewise be represented by the matrix</p> |
− | | and the application of these rules to the above values of
| + | |- |
− | | 1, i, j, k gives the quaternion relations
| + | | align="center" | |
| + | <math>\begin{array}{rr} |
| + | x & y |
| + | \\ |
| + | -y & x |
| + | \end{array}</math> |
| + | |- |
| | | | | |
− | | i^2 = j^2 = k^2 = -1,
| + | <p>and the determinant of the matrix = the square of the modulus.</p> |
− | |
| + | |
− | | ijk = -1,
| + | <p>C.S. Peirce, ''Johns Hopkins University Circulars'', No. 13, p. 179, 1882. Reprinted, ''Collected Papers'', CP 3.323.</p> |
− | |
| + | |} |
− | | etc.
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− | |
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− | | The symbol a(Y:Z) denotes the changing of Y to Z and the
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− | | multiplication of the result by 'a'. If the relatives be
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− | | arranged in a block
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− | |
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− | | W:W W:X W:Y W:Z
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− | |
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− | | X:W X:X X:Y X:Z
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− | |
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− | | Y:W Y:X Y:Y Y:Z
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− | |
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− | | Z:W Z:X Z:Y Z:Z
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− | |
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− | | then the quaternion w + xi + yj + zk
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− | | is represented by the matrix of numbers
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− | |
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− | | w -x -y -z
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− | |
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− | | x w -z y
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− | |
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− | | y z w -x
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− | |
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− | | z -y x w
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− | |
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− | | The multiplication of such matrices follows the same laws as the
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− | | multiplication of quaternions. The determinant of the matrix =
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− | | the fourth power of the tensor of the quaternion.
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− | |
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− | | The imaginary x + y(-1)^(1/2) may likewise be represented by the matrix
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− | |
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− | | x y
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− | |
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− | | -y x
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− | |
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− | | and the determinant of the matrix = the square of the modulus.
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− | |
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− | | Charles Sanders Peirce, 'Collected Papers', CP 3.323.
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− | |'Johns Hopkins University Circulars', No. 13, p. 179, 1882.
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− | </pre> | |
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| This way of talking is the mark of a person who opts to multiply his matrices "on the rignt", as they say. Yet Peirce still continues to call the first element of the ordered pair <math>(I:J)\!</math> its "relate" while calling the second element of the pair <math>(I:J)\!</math> its "correlate". That doesn't comport very well, so far as I can tell, with his customary reading of relative terms, suited more to the multiplication of matrices "on the left". | | This way of talking is the mark of a person who opts to multiply his matrices "on the rignt", as they say. Yet Peirce still continues to call the first element of the ordered pair <math>(I:J)\!</math> its "relate" while calling the second element of the pair <math>(I:J)\!</math> its "correlate". That doesn't comport very well, so far as I can tell, with his customary reading of relative terms, suited more to the multiplication of matrices "on the left". |