Miscellaneous

This page documents the miscellaneous members of the blosc2 module that do not fit into other categories.

blosc2.cpu_info = {'count': 4, 'l1_data_cache_size': 32768, 'l2_cache_size': 1048576, 'l3_cache_size': 33554432}

class blosc2.finfo(dtype)

Machine limits for floating point types.

bits

The number of bits occupied by the type.

Type:

int

dtype

Returns the dtype for which finfo returns information. For complex input, the returned dtype is the associated float* dtype for its real and complex components.

Type:

dtype

eps

The difference between 1.0 and the next smallest representable float larger than 1.0. For example, for 64-bit binary floats in the IEEE-754 standard, eps = 2**-52, approximately 2.22e-16.

Type:

float

epsneg

The difference between 1.0 and the next smallest representable float less than 1.0. For example, for 64-bit binary floats in the IEEE-754 standard, epsneg = 2**-53, approximately 1.11e-16.

Type:

float

iexp

The number of bits in the exponent portion of the floating point representation.

Type:

int

machep

The exponent that yields eps.

Type:

int

max

The largest representable number.

Type:

floating point number of the appropriate type

maxexp

The smallest positive power of the base (2) that causes overflow. Corresponds to the C standard MAX_EXP.

Type:

int

min

The smallest representable number, typically -max.

Type:

floating point number of the appropriate type

minexp

The most negative power of the base (2) consistent with there being no leading 0’s in the mantissa. Corresponds to the C standard MIN_EXP - 1.

Type:

int

negep

The exponent that yields epsneg.

Type:

int

nexp

The number of bits in the exponent including its sign and bias.

Type:

int

nmant

The number of explicit bits in the mantissa (excluding the implicit leading bit for normalized numbers).

Type:

int

precision

The approximate number of decimal digits to which this kind of float is precise.

Type:

int

resolution

The approximate decimal resolution of this type, i.e., 10**-precision.

Type:

floating point number of the appropriate type

tiny

An alias for smallest_normal, kept for backwards compatibility.

Type:

float

smallest_normal

The smallest positive floating point number with 1 as leading bit in the mantissa following IEEE-754 (see Notes).

Type:

float

smallest_subnormal

The smallest positive floating point number with 0 as leading bit in the mantissa following IEEE-754.

Type:

float

Parameters:

dtype (float, dtype, or instance) – Kind of floating point or complex floating point data-type about which to get information.

See also

iinfo

The equivalent for integer data types.

spacing

The distance between a value and the nearest adjacent number

nextafter

The next floating point value after x1 towards x2

Notes

For developers of NumPy: do not instantiate this at the module level. The initial calculation of these parameters is expensive and negatively impacts import times. These objects are cached, so calling finfo() repeatedly inside your functions is not a problem.

Note that smallest_normal is not actually the smallest positive representable value in a NumPy floating point type. As in the IEEE-754 standard [1], NumPy floating point types make use of subnormal numbers to fill the gap between 0 and smallest_normal. However, subnormal numbers may have significantly reduced precision [2].

For longdouble, the representation varies across platforms. On most platforms it is IEEE 754 binary128 (quad precision) or binary64-extended (80-bit extended precision). On PowerPC systems, it may use the IBM double-double format (a pair of float64 values), which has special characteristics for precision and range.

This function can also be used for complex data types as well. If used, the output will be the same as the corresponding real float type (e.g. numpy.finfo(numpy.csingle) is the same as numpy.finfo(numpy.single)). However, the output is true for the real and imaginary components.

References

[1]

IEEE Standard for Floating-Point Arithmetic, IEEE Std 754-2008, pp.1-70, 2008, https://doi.org/10.1109/IEEESTD.2008.4610935

[2]

Wikipedia, “Denormal Numbers”, https://en.wikipedia.org/wiki/Denormal_number

Examples

>>> import numpy as np
>>> np.finfo(np.float64).dtype
dtype('float64')
>>> np.finfo(np.complex64).dtype
dtype('float32')

Attributes:

epsneg

iexp

machep

negep

nexp

resolution

tiny

Return the value for tiny, alias of smallest_normal.

tinyfloat

Value for the smallest normal, alias of smallest_normal.

UserWarning

If the calculated value for the smallest normal is requested for double-double.

class blosc2.iinfo(type)

Machine limits for integer types.

bits

The number of bits occupied by the type.

Type:

int

dtype

Returns the dtype for which iinfo returns information.

Type:

dtype

min

The smallest integer expressible by the type.

Type:

int

max

The largest integer expressible by the type.

Type:

int

Parameters:

int_type (integer type, dtype, or instance) – The kind of integer data type to get information about.

See also

finfo

The equivalent for floating point data types.

Examples

With types:

>>> import numpy as np
>>> ii16 = np.iinfo(np.int16)
>>> ii16.min
-32768
>>> ii16.max
32767
>>> ii32 = np.iinfo(np.int32)
>>> ii32.min
-2147483648
>>> ii32.max
2147483647

With instances:

>>> ii32 = np.iinfo(np.int32(10))
>>> ii32.min
-2147483648
>>> ii32.max
2147483647

Attributes:

max

Maximum value of given dtype.

min

Minimum value of given dtype.

blosc2.get_matmul_library() → str | None

Return the library used by the active matmul fast backend, if any.

Returns:

"Accelerate.framework" when the selected backend is Accelerate, the loaded CBLAS library path for runtime-discovered CBLAS backends, or None when the selected backend is naive.

Return type:

str | None

Unclassified module members

The list below is intentionally generated from blosc2 module members that are not excluded above. It acts as a reminder to classify newly documented public objects into the appropriate reference section.