1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
|
function C = gb_power (A, B)
%GB_POWER .^ Array power.
% C = A.^B computes element-wise powers.
% SuiteSparse:GraphBLAS, Timothy A. Davis, (c) 2017-2022, All Rights Reserved.
% SPDX-License-Identifier: Apache-2.0
[am, an, atype] = gbsize (A) ;
[bm, bn, btype] = gbsize (B) ;
a_is_scalar = (am == 1) && (an == 1) ;
b_is_scalar = (bm == 1) && (bn == 1) ;
a_is_real = ~gb_contains (atype, 'complex') ;
b_is_real = ~gb_contains (btype, 'complex') ;
% determine if C = A.^B is real or complex
if (a_is_real && b_is_real)
% A and B are both real. Determine if C might be complex.
if (gb_contains (btype, 'int') || isequal (btype, 'logical'))
% B is logical or integer, so C is real
c_is_real = true ;
elseif (gbisequal (B, gbapply ('round', B)))
% B is floating point, but all values are equal to integers
c_is_real = true ;
elseif (gb_scalar (gbreduce ('min', A)) >= 0)
% All entries in A are non-negative, so C is real
c_is_real = true ;
else
% A has negative entries, and B is non-integer, so C can be complex.
c_is_real = false ;
end
else
% A or B are complex, or both, so C must be complex
c_is_real = false ;
end
if (c_is_real)
% C is real
ctype = gboptype (atype, btype) ;
else
% C is complex
if (gb_contains (atype, 'single') && gb_contains (btype, 'single'))
ctype = 'single complex' ;
else
ctype = 'double complex' ;
end
end
% B is always full
B = gbfull (B, ctype) ;
% determine the operator
op = ['pow.' ctype] ;
if (a_is_scalar)
%----------------------------------------------------------------------
% A is a scalar: C is a full matrix
%----------------------------------------------------------------------
C = gbapply2 (op, gbfull (A, ctype), B) ;
else
%----------------------------------------------------------------------
% A is a matrix
%----------------------------------------------------------------------
if (b_is_scalar)
% A is a matrix, B is a scalar
b = gb_scalar (B) ;
if (b == 0)
% special case: C = A.^0 = ones (am, an, ctype)
C = gb_scalar_to_full (am, an, ctype, gb_fmt (A), 1) ;
return ;
elseif (b == 1)
% special case: C = A.^1 = A
C = A ;
return
elseif (b <= 0)
% 0.^b where b < 0 is Inf, so C is full
C = gbapply2 (op, gbfull (A, ctype), B) ;
else
% The scalar b is > 0, and thus 0.^b is zero, so C is sparse.
C = gbapply2 (op, A, B) ;
end
else
% both A and B are matrices. 0.^0 is 1, so C is full.
C = gbemult (op, gbfull (A, ctype), B) ;
end
end
% convert C to real if imaginary part is zero
if (~c_is_real)
C = gb_check_imag_zero (C) ;
end
|
