# LogQuantity#

class astropy.units.function.logarithmic.LogQuantity(value, unit=None, dtype=<class 'numpy.inexact'>, copy=True, order=None, subok=False, ndmin=0)[source]#

A representation of a (scaled) logarithm of a number with a unit.

Parameters:
valuenumber, `Quantity`, `LogQuantity`, or sequence of quantity-like.

The numerical value of the logarithmic quantity. If a number or a `Quantity` with a logarithmic unit, it will be converted to `unit` and the physical unit will be inferred from `unit`. If a `Quantity` with just a physical unit, it will converted to the logarithmic unit, after, if necessary, converting it to the physical unit inferred from `unit`.

unit`str`, `UnitBase`, or `FunctionUnitBase`, optional

For an `FunctionUnitBase` instance, the physical unit will be taken from it; for other input, it will be inferred from `value`. By default, `unit` is set by the subclass.

dtype`dtype`, optional

The `dtype` of the resulting Numpy array or scalar that will hold the value. If not provided, is is determined automatically from the input value.

copybool, optional

If `True` (default), then the value is copied. Otherwise, a copy will only be made if `__array__` returns a copy, if value is a nested sequence, or if a copy is needed to satisfy an explicitly given `dtype`. (The `False` option is intended mostly for internal use, to speed up initialization where a copy is known to have been made. Use with care.)

Examples

Typically, use is made of an `FunctionQuantity` subclass, as in:

```>>> import astropy.units as u
>>> u.Magnitude(-2.5)
<Magnitude -2.5 mag>
>>> u.Magnitude(10.*u.count/u.second)
<Magnitude -2.5 mag(ct / s)>
>>> u.Decibel(1.*u.W, u.DecibelUnit(u.mW))
<Decibel 30. dB(mW)>
```

Methods Summary

 `diff`([n, axis]) `ediff1d`([to_end, to_begin]) `ptp`([axis, out, keepdims]) Peak to peak (maximum - minimum) value along a given axis. `std`([axis, dtype, out, ddof, keepdims, where]) Returns the standard deviation of the array elements along given axis. `var`([axis, dtype, out, ddof, keepdims, where]) Returns the variance of the array elements, along given axis.

Methods Documentation

diff(n=1, axis=-1)[source]#
ediff1d(to_end=None, to_begin=None)[source]#
ptp(axis=None, out=None, keepdims=False)[source]#

Peak to peak (maximum - minimum) value along a given axis.

Refer to `numpy.ptp` for full documentation.

`numpy.ptp`

equivalent function

std(axis=None, dtype=None, out=None, ddof=0, keepdims=False, *, where=True)[source]#

Returns the standard deviation of the array elements along given axis.

Refer to `numpy.std` for full documentation.

`numpy.std`

equivalent function

var(axis=None, dtype=None, out=None, ddof=0, keepdims=False, *, where=True)[source]#

Returns the variance of the array elements, along given axis.

Refer to `numpy.var` for full documentation.

`numpy.var`