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### B.1.2 Maths

Standard mathematical and trigonometric functions.

E
  Euler's number e, the base of natural logarithms.
PI
  Pi, the ratio of the circumference of a circle to its diameter.
RANDOM
  Evaluates to a random number in the range 0<=x<1. This is different for each cell of the table. The quality of the randomness may not be particularly good.
sin( theta )
  Sine of an angle.
cos( theta )
  Cosine of an angle.
tan( theta )
  Tangent of an angle.
asin( x )
  Arc sine of an angle. The result is in the range of -pi/2 through pi/2.
acos( x )
  Arc cosine of an angle. The result is in the range of 0.0 through pi.
atan( x )
  Arc tangent of an angle. The result is in the range of -pi/2 through pi/2.
exp( x )
  Euler's number e raised to a power.
log10( x )
  Logarithm to base 10.
ln( x )
  Natural logarithm.
sqrt( x )
  Square root. The result is correctly rounded and positive.
atan2( y, x )
  Converts rectangular coordinates (`x`,`y`) to polar (`r`,`theta`). This method computes the phase `theta` by computing an arc tangent of `y/x` in the range of -pi to pi.
pow( a, b )
  Exponentiation. The result is the value of the first argument raised to the power of the second argument.
sinh( x )
  Hyperbolic sine.
cosh( x )
  Hyperbolic cosine.
tanh( x )
  Hyperbolic tangent.
asinh( x )
  Inverse hyperbolic sine.
acosh( x )
  Inverse hyperbolic cosine.
atanh( x )
  Inverse hyperbolic tangent.

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TOPCAT - Tool for OPerations on Catalogues And Tables
Starlink User Note253
TOPCAT web page: http://www.starlink.ac.uk/topcat/
Author email: m.b.taylor@bristol.ac.uk
Mailing list: topcat-user@bristol.ac.uk