:func:`acos(x) <acos>` Arc cosine of *x*, in radians

:func:`acospi(x) <acospi>` Arc cosine of *x*, in half-turns

:func:`asin(x) <asin>` Arc sine of *x*, in radians

:func:`asinpi(x) <asinpi>` Arc sine of *x*, in half-turns

:func:`atan(x) <atan>` Arc tangent of *x*, in radians

:func:`atanpi(x) <atanpi>` Arc tangent of *x*, in half-turns

:func:`atan2(y, x) <atan2>` ``atan(y / x)``, in radians

:func:`atan2pi(y, x) <atan2pi>` ``atan(y / x)``, in half-turns

:func:`cos(x) <cos>` Cosine of *x* radians

:func:`cospi(x) <cospi>` Cosine of *x⋅π* radians

:func:`sin(x) <sin>` Sine of *x* radians

:func:`sinpi(x) <sinpi>` Sine of *x⋅π* radians

:func:`tan(x) <tan>` Tangent of *x* radians

:func:`tanpi(x) <tanpi>` Tangent of *x⋅π* radians

.. function:: acospi(x)

Return the arc cosine of *x*, in half-turns. The result is between ``0`` and

``1``.

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.. function:: asinpi(x)

Return the arc sine of *x*, in half-turns. The result is between ``-0.5`` and

``0.5``.

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.. function:: atanpi(x)

Return the arc tangent of *x*, in half-turns. The result is between ``-0.5`` and

``0.5``.

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.. function:: atan2pi(y, x)

Return ``atanpi(y / x)``, in half-turns. The result is between ``-1`` and ``1``.

The vector in the plane from the origin to point ``(x, y)`` makes this angle

with the positive X axis. The point of :func:`atan2pi` is that the signs of both

inputs are known to it, so it can compute the correct quadrant for the angle.

For example, ``atanpi(1)`` and ``atan2pi(1, 1)`` are both ``0.25``, but

``atan2pi(-1, -1)`` is ``-0.75``.

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.. function:: cospi(x)

Return the cosine of *x* half-turns (*x⋅π* radians).

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.. function:: sinpi(x)

Return the sine of *x* half-turns (*x⋅π* radians).

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.. function:: tanpi(x)

Return the tangent of *x* half-turns (*x⋅π* radians).

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