Mercurial > hg > vamp-build-and-test
diff DEPENDENCIES/mingw32/Python27/Lib/site-packages/numpy/lib/scimath.py @ 87:2a2c65a20a8b
Add Python libs and headers
| author | Chris Cannam |
|---|---|
| date | Wed, 25 Feb 2015 14:05:22 +0000 |
| parents | |
| children |
line wrap: on
line diff
--- /dev/null Thu Jan 01 00:00:00 1970 +0000 +++ b/DEPENDENCIES/mingw32/Python27/Lib/site-packages/numpy/lib/scimath.py Wed Feb 25 14:05:22 2015 +0000 @@ -0,0 +1,566 @@ +""" +Wrapper functions to more user-friendly calling of certain math functions +whose output data-type is different than the input data-type in certain +domains of the input. + +For example, for functions like `log` with branch cuts, the versions in this +module provide the mathematically valid answers in the complex plane:: + + >>> import math + >>> from numpy.lib import scimath + >>> scimath.log(-math.exp(1)) == (1+1j*math.pi) + True + +Similarly, `sqrt`, other base logarithms, `power` and trig functions are +correctly handled. See their respective docstrings for specific examples. + +""" +from __future__ import division, absolute_import, print_function + +import numpy.core.numeric as nx +import numpy.core.numerictypes as nt +from numpy.core.numeric import asarray, any +from numpy.lib.type_check import isreal + + +__all__ = [ + 'sqrt', 'log', 'log2', 'logn', 'log10', 'power', 'arccos', 'arcsin', + 'arctanh' + ] + + +_ln2 = nx.log(2.0) + + +def _tocomplex(arr): + """Convert its input `arr` to a complex array. + + The input is returned as a complex array of the smallest type that will fit + the original data: types like single, byte, short, etc. become csingle, + while others become cdouble. + + A copy of the input is always made. + + Parameters + ---------- + arr : array + + Returns + ------- + array + An array with the same input data as the input but in complex form. + + Examples + -------- + + First, consider an input of type short: + + >>> a = np.array([1,2,3],np.short) + + >>> ac = np.lib.scimath._tocomplex(a); ac + array([ 1.+0.j, 2.+0.j, 3.+0.j], dtype=complex64) + + >>> ac.dtype + dtype('complex64') + + If the input is of type double, the output is correspondingly of the + complex double type as well: + + >>> b = np.array([1,2,3],np.double) + + >>> bc = np.lib.scimath._tocomplex(b); bc + array([ 1.+0.j, 2.+0.j, 3.+0.j]) + + >>> bc.dtype + dtype('complex128') + + Note that even if the input was complex to begin with, a copy is still + made, since the astype() method always copies: + + >>> c = np.array([1,2,3],np.csingle) + + >>> cc = np.lib.scimath._tocomplex(c); cc + array([ 1.+0.j, 2.+0.j, 3.+0.j], dtype=complex64) + + >>> c *= 2; c + array([ 2.+0.j, 4.+0.j, 6.+0.j], dtype=complex64) + + >>> cc + array([ 1.+0.j, 2.+0.j, 3.+0.j], dtype=complex64) + """ + if issubclass(arr.dtype.type, (nt.single, nt.byte, nt.short, nt.ubyte, + nt.ushort, nt.csingle)): + return arr.astype(nt.csingle) + else: + return arr.astype(nt.cdouble) + +def _fix_real_lt_zero(x): + """Convert `x` to complex if it has real, negative components. + + Otherwise, output is just the array version of the input (via asarray). + + Parameters + ---------- + x : array_like + + Returns + ------- + array + + Examples + -------- + >>> np.lib.scimath._fix_real_lt_zero([1,2]) + array([1, 2]) + + >>> np.lib.scimath._fix_real_lt_zero([-1,2]) + array([-1.+0.j, 2.+0.j]) + + """ + x = asarray(x) + if any(isreal(x) & (x < 0)): + x = _tocomplex(x) + return x + +def _fix_int_lt_zero(x): + """Convert `x` to double if it has real, negative components. + + Otherwise, output is just the array version of the input (via asarray). + + Parameters + ---------- + x : array_like + + Returns + ------- + array + + Examples + -------- + >>> np.lib.scimath._fix_int_lt_zero([1,2]) + array([1, 2]) + + >>> np.lib.scimath._fix_int_lt_zero([-1,2]) + array([-1., 2.]) + """ + x = asarray(x) + if any(isreal(x) & (x < 0)): + x = x * 1.0 + return x + +def _fix_real_abs_gt_1(x): + """Convert `x` to complex if it has real components x_i with abs(x_i)>1. + + Otherwise, output is just the array version of the input (via asarray). + + Parameters + ---------- + x : array_like + + Returns + ------- + array + + Examples + -------- + >>> np.lib.scimath._fix_real_abs_gt_1([0,1]) + array([0, 1]) + + >>> np.lib.scimath._fix_real_abs_gt_1([0,2]) + array([ 0.+0.j, 2.+0.j]) + """ + x = asarray(x) + if any(isreal(x) & (abs(x) > 1)): + x = _tocomplex(x) + return x + +def sqrt(x): + """ + Compute the square root of x. + + For negative input elements, a complex value is returned + (unlike `numpy.sqrt` which returns NaN). + + Parameters + ---------- + x : array_like + The input value(s). + + Returns + ------- + out : ndarray or scalar + The square root of `x`. If `x` was a scalar, so is `out`, + otherwise an array is returned. + + See Also + -------- + numpy.sqrt + + Examples + -------- + For real, non-negative inputs this works just like `numpy.sqrt`: + + >>> np.lib.scimath.sqrt(1) + 1.0 + >>> np.lib.scimath.sqrt([1, 4]) + array([ 1., 2.]) + + But it automatically handles negative inputs: + + >>> np.lib.scimath.sqrt(-1) + (0.0+1.0j) + >>> np.lib.scimath.sqrt([-1,4]) + array([ 0.+1.j, 2.+0.j]) + + """ + x = _fix_real_lt_zero(x) + return nx.sqrt(x) + +def log(x): + """ + Compute the natural logarithm of `x`. + + Return the "principal value" (for a description of this, see `numpy.log`) + of :math:`log_e(x)`. For real `x > 0`, this is a real number (``log(0)`` + returns ``-inf`` and ``log(np.inf)`` returns ``inf``). Otherwise, the + complex principle value is returned. + + Parameters + ---------- + x : array_like + The value(s) whose log is (are) required. + + Returns + ------- + out : ndarray or scalar + The log of the `x` value(s). If `x` was a scalar, so is `out`, + otherwise an array is returned. + + See Also + -------- + numpy.log + + Notes + ----- + For a log() that returns ``NAN`` when real `x < 0`, use `numpy.log` + (note, however, that otherwise `numpy.log` and this `log` are identical, + i.e., both return ``-inf`` for `x = 0`, ``inf`` for `x = inf`, and, + notably, the complex principle value if ``x.imag != 0``). + + Examples + -------- + >>> np.emath.log(np.exp(1)) + 1.0 + + Negative arguments are handled "correctly" (recall that + ``exp(log(x)) == x`` does *not* hold for real ``x < 0``): + + >>> np.emath.log(-np.exp(1)) == (1 + np.pi * 1j) + True + + """ + x = _fix_real_lt_zero(x) + return nx.log(x) + +def log10(x): + """ + Compute the logarithm base 10 of `x`. + + Return the "principal value" (for a description of this, see + `numpy.log10`) of :math:`log_{10}(x)`. For real `x > 0`, this + is a real number (``log10(0)`` returns ``-inf`` and ``log10(np.inf)`` + returns ``inf``). Otherwise, the complex principle value is returned. + + Parameters + ---------- + x : array_like or scalar + The value(s) whose log base 10 is (are) required. + + Returns + ------- + out : ndarray or scalar + The log base 10 of the `x` value(s). If `x` was a scalar, so is `out`, + otherwise an array object is returned. + + See Also + -------- + numpy.log10 + + Notes + ----- + For a log10() that returns ``NAN`` when real `x < 0`, use `numpy.log10` + (note, however, that otherwise `numpy.log10` and this `log10` are + identical, i.e., both return ``-inf`` for `x = 0`, ``inf`` for `x = inf`, + and, notably, the complex principle value if ``x.imag != 0``). + + Examples + -------- + + (We set the printing precision so the example can be auto-tested) + + >>> np.set_printoptions(precision=4) + + >>> np.emath.log10(10**1) + 1.0 + + >>> np.emath.log10([-10**1, -10**2, 10**2]) + array([ 1.+1.3644j, 2.+1.3644j, 2.+0.j ]) + + """ + x = _fix_real_lt_zero(x) + return nx.log10(x) + +def logn(n, x): + """ + Take log base n of x. + + If `x` contains negative inputs, the answer is computed and returned in the + complex domain. + + Parameters + ---------- + n : int + The base in which the log is taken. + x : array_like + The value(s) whose log base `n` is (are) required. + + Returns + ------- + out : ndarray or scalar + The log base `n` of the `x` value(s). If `x` was a scalar, so is + `out`, otherwise an array is returned. + + Examples + -------- + >>> np.set_printoptions(precision=4) + + >>> np.lib.scimath.logn(2, [4, 8]) + array([ 2., 3.]) + >>> np.lib.scimath.logn(2, [-4, -8, 8]) + array([ 2.+4.5324j, 3.+4.5324j, 3.+0.j ]) + + """ + x = _fix_real_lt_zero(x) + n = _fix_real_lt_zero(n) + return nx.log(x)/nx.log(n) + +def log2(x): + """ + Compute the logarithm base 2 of `x`. + + Return the "principal value" (for a description of this, see + `numpy.log2`) of :math:`log_2(x)`. For real `x > 0`, this is + a real number (``log2(0)`` returns ``-inf`` and ``log2(np.inf)`` returns + ``inf``). Otherwise, the complex principle value is returned. + + Parameters + ---------- + x : array_like + The value(s) whose log base 2 is (are) required. + + Returns + ------- + out : ndarray or scalar + The log base 2 of the `x` value(s). If `x` was a scalar, so is `out`, + otherwise an array is returned. + + See Also + -------- + numpy.log2 + + Notes + ----- + For a log2() that returns ``NAN`` when real `x < 0`, use `numpy.log2` + (note, however, that otherwise `numpy.log2` and this `log2` are + identical, i.e., both return ``-inf`` for `x = 0`, ``inf`` for `x = inf`, + and, notably, the complex principle value if ``x.imag != 0``). + + Examples + -------- + We set the printing precision so the example can be auto-tested: + + >>> np.set_printoptions(precision=4) + + >>> np.emath.log2(8) + 3.0 + >>> np.emath.log2([-4, -8, 8]) + array([ 2.+4.5324j, 3.+4.5324j, 3.+0.j ]) + + """ + x = _fix_real_lt_zero(x) + return nx.log2(x) + +def power(x, p): + """ + Return x to the power p, (x**p). + + If `x` contains negative values, the output is converted to the + complex domain. + + Parameters + ---------- + x : array_like + The input value(s). + p : array_like of ints + The power(s) to which `x` is raised. If `x` contains multiple values, + `p` has to either be a scalar, or contain the same number of values + as `x`. In the latter case, the result is + ``x[0]**p[0], x[1]**p[1], ...``. + + Returns + ------- + out : ndarray or scalar + The result of ``x**p``. If `x` and `p` are scalars, so is `out`, + otherwise an array is returned. + + See Also + -------- + numpy.power + + Examples + -------- + >>> np.set_printoptions(precision=4) + + >>> np.lib.scimath.power([2, 4], 2) + array([ 4, 16]) + >>> np.lib.scimath.power([2, 4], -2) + array([ 0.25 , 0.0625]) + >>> np.lib.scimath.power([-2, 4], 2) + array([ 4.+0.j, 16.+0.j]) + + """ + x = _fix_real_lt_zero(x) + p = _fix_int_lt_zero(p) + return nx.power(x, p) + +def arccos(x): + """ + Compute the inverse cosine of x. + + Return the "principal value" (for a description of this, see + `numpy.arccos`) of the inverse cosine of `x`. For real `x` such that + `abs(x) <= 1`, this is a real number in the closed interval + :math:`[0, \\pi]`. Otherwise, the complex principle value is returned. + + Parameters + ---------- + x : array_like or scalar + The value(s) whose arccos is (are) required. + + Returns + ------- + out : ndarray or scalar + The inverse cosine(s) of the `x` value(s). If `x` was a scalar, so + is `out`, otherwise an array object is returned. + + See Also + -------- + numpy.arccos + + Notes + ----- + For an arccos() that returns ``NAN`` when real `x` is not in the + interval ``[-1,1]``, use `numpy.arccos`. + + Examples + -------- + >>> np.set_printoptions(precision=4) + + >>> np.emath.arccos(1) # a scalar is returned + 0.0 + + >>> np.emath.arccos([1,2]) + array([ 0.-0.j , 0.+1.317j]) + + """ + x = _fix_real_abs_gt_1(x) + return nx.arccos(x) + +def arcsin(x): + """ + Compute the inverse sine of x. + + Return the "principal value" (for a description of this, see + `numpy.arcsin`) of the inverse sine of `x`. For real `x` such that + `abs(x) <= 1`, this is a real number in the closed interval + :math:`[-\\pi/2, \\pi/2]`. Otherwise, the complex principle value is + returned. + + Parameters + ---------- + x : array_like or scalar + The value(s) whose arcsin is (are) required. + + Returns + ------- + out : ndarray or scalar + The inverse sine(s) of the `x` value(s). If `x` was a scalar, so + is `out`, otherwise an array object is returned. + + See Also + -------- + numpy.arcsin + + Notes + ----- + For an arcsin() that returns ``NAN`` when real `x` is not in the + interval ``[-1,1]``, use `numpy.arcsin`. + + Examples + -------- + >>> np.set_printoptions(precision=4) + + >>> np.emath.arcsin(0) + 0.0 + + >>> np.emath.arcsin([0,1]) + array([ 0. , 1.5708]) + + """ + x = _fix_real_abs_gt_1(x) + return nx.arcsin(x) + +def arctanh(x): + """ + Compute the inverse hyperbolic tangent of `x`. + + Return the "principal value" (for a description of this, see + `numpy.arctanh`) of `arctanh(x)`. For real `x` such that + `abs(x) < 1`, this is a real number. If `abs(x) > 1`, or if `x` is + complex, the result is complex. Finally, `x = 1` returns``inf`` and + `x=-1` returns ``-inf``. + + Parameters + ---------- + x : array_like + The value(s) whose arctanh is (are) required. + + Returns + ------- + out : ndarray or scalar + The inverse hyperbolic tangent(s) of the `x` value(s). If `x` was + a scalar so is `out`, otherwise an array is returned. + + + See Also + -------- + numpy.arctanh + + Notes + ----- + For an arctanh() that returns ``NAN`` when real `x` is not in the + interval ``(-1,1)``, use `numpy.arctanh` (this latter, however, does + return +/-inf for `x = +/-1`). + + Examples + -------- + >>> np.set_printoptions(precision=4) + + >>> np.emath.arctanh(np.matrix(np.eye(2))) + array([[ Inf, 0.], + [ 0., Inf]]) + >>> np.emath.arctanh([1j]) + array([ 0.+0.7854j]) + + """ + x = _fix_real_abs_gt_1(x) + return nx.arctanh(x)