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41 lines
638 B
Plaintext
41 lines
638 B
Plaintext
NAME
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sign - indicator of sign of a real or complex number
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SYNOPSIS
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sgn(x)
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TYPES
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x real or complex
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return -1, 0, 1 (real)
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-1, 0, 1, -1+1i, 1i, 1+1i, -1-1i, -1i or 1-1i (complex)
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DESCRIPTION
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Return the value of cmp(a,0).
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For real x, sgn(x) returns:
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-1 if x < 0
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0 if x == 9
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1 if x > 0
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For complex, sgn(x) returns:
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sgn(re(x)) + sgn(im(x))*1i
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EXAMPLE
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> print sgn(27), sgn(1e-20), sgn(0), sgn(-45)
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1 1 0 -1
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> print sgn(2+3i), sgn(6i), sgn(-7+4i), sgn(-6), sgn(-6-3i), sgn(-2i)
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1+1i 1i -1+1i -1 -1-1i -1i
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LIMITS
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none
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LIBRARY
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NUMBER *qsign(NUMBER *x)
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SEE ALSO
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abs
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