Next Previous Up Contents
Next: Randoms
Up: General Functions
Previous: Lists
Standard mathematical and trigonometric functions.
Trigonometric functions work with angles in radians.
-
sin( theta )
-
Sine of an angle.
- Parameters:
-
theta
(floating point): an angle, in radians.
- Return value
-
(floating point): the sine of the argument.
-
cos( theta )
-
Cosine of an angle.
- Parameters:
-
theta
(floating point): an angle, in radians.
- Return value
-
(floating point): the cosine of the argument.
-
tan( theta )
-
Tangent of an angle.
- Parameters:
-
theta
(floating point): an angle, in radians.
- Return value
-
(floating point): the tangent of the argument.
-
asin( x )
-
Arc sine of an angle.
The result is in the range of -pi/2 through
pi/2.
- Parameters:
-
x
(floating point): the value whose arc sine is to be returned.
- Return value
-
(floating point): the arc sine of the argument (radians)
-
acos( x )
-
Arc cosine of an angle.
The result is in the range of 0.0 through pi.
- Parameters:
-
x
(floating point): the value whose arc cosine is to be returned.
- Return value
-
(floating point): the arc cosine of the argument (radians)
-
atan( x )
-
Arc tangent of an angle.
The result is in the range of -pi/2 through pi/2.
- Parameters:
-
x
(floating point): the value whose arc tangent is to be returned.
- Return value
-
(floating point): the arc tangent of the argument (radians)
-
ln( x )
-
Natural logarithm.
- Parameters:
-
x
(floating point): argument
- Return value
-
(floating point): loge(x)
-
exp( x )
-
Euler's number e raised to a power.
- Parameters:
-
x
(floating point): the exponent to raise e to.
- Return value
-
(floating point): the value ex,
where e is the base of the natural logarithms.
-
log10( x )
-
Logarithm to base 10.
- Parameters:
-
x
(floating point): argument
- Return value
-
(floating point): log10(x)
-
exp10( x )
-
Power of 10.
This convenience function is identical to
pow(10,x)
.
- Parameters:
-
x
(floating point): argument
- Return value
-
sqrt( x )
-
Square root.
The result is correctly rounded and positive.
- Parameters:
-
x
(floating point): a value.
- Return value
-
(floating point): the positive square root of
x
.
If the argument is NaN or less than zero, the result is NaN.
-
square( x )
-
Raise to the power 2.
- Parameters:
-
x
(floating point): a value
- Return value
-
hypot( xs, ... )
-
Returns the square root of the sum of squares of its arguments.
In the 2-argument case, doing it like this may avoid intermediate
overflow or underflow.
- Parameters:
-
xs
(floating point, one or more): one or more numeric values
- Return value
-
(floating point): sqare root of sum of squares of arguments
- Examples:
-
hypot(3,4) = 5
-
hypot(2,2,2,2) = 4
-
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.
- Parameters:
-
y
(floating point): the ordinate coordinate
-
x
(floating point): the abscissa coordinate
- Return value
-
(floating point): the
theta
component (radians) of the point
(r
,theta
)
in polar coordinates that corresponds to the point
(x
,y
) in Cartesian coordinates.
-
pow( a, b )
-
Exponentiation.
The result is the value of the first argument raised to
the power of the second argument.
- Parameters:
-
a
(floating point): the base.
-
b
(floating point): the exponent.
- Return value
-
(floating point): the value
ab
.
-
sinh( x )
-
Hyperbolic sine.
- Parameters:
-
x
(floating point): parameter
- Return value
-
cosh( x )
-
Hyperbolic cosine.
- Parameters:
-
x
(floating point): parameter
- Return value
-
tanh( x )
-
Hyperbolic tangent.
- Parameters:
-
x
(floating point): parameter
- Return value
-
asinh( x )
-
Inverse hyperbolic sine.
- Parameters:
-
x
(floating point): parameter
- Return value
-
acosh( x )
-
Inverse hyperbolic cosine.
- Parameters:
-
x
(floating point): parameter
- Return value
-
atanh( x )
-
Inverse hyperbolic tangent.
- Parameters:
-
x
(floating point): parameter
- Return value
-
E
-
Euler's number e, the base of natural logarithms.
-
PI
-
Pi, the ratio of the circumference of a circle to its diameter.
-
Infinity
-
Positive infinite floating point value.
-
NaN
-
Not-a-Number floating point value.
Use with care; arithmetic and logical operations behave in strange
ways near NaN (for instance,
NaN!=NaN
).
For most purposes this is equivalent to the blank value.
Next Previous Up Contents
Next: Randoms
Up: General Functions
Previous: Lists
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@jiscmail.ac.uk