sum
sum of array elements
Syntax
y = sum(x) y = sum(x, outtype) y = sum(x, orientation) y = sum(x, orientation, outtype)
Arguments
- x
- Array of booleans (full or sparse), encoded integers, real or complex numbers (full or sparse), polynomials, or rationals.
- orientation
- it can be either
- a character
"*"
(default),"r"
,"c"
or"m"
- a positive integer: Index of the dimension along which the sums must be computed.
- a character
- outtype
- string
"native"
or"double"
. - y
- scalar or array
Description
For an array x
,
y=sum(x)
returns in the scalar y
the
sum of all the elements of x
.
y=sum(x,orientation)
returns in
y
the sum of x
along the
dimension given by orientation
:
if
orientation
is equal to 1 or "r" thenor
if
orientation
is equal to 2 or "c" then:or
if
orientation
is equal to n theny=sum(x,"*")
is equivalent toy=sum(x)
y=sum(x,"m")
is equivalent toy=sum(x,orientation)
whereorientation
is the index of the first dimension ofx
that is greater than 1.
The outtype
argument rules the way the summation is done:
For arrays of floats, of polynomials, of rational fractions, the evaluation is always done using floating points computations. The
"double"
or"native"
options are equivalent.For arrays of integers,
if
outtype="native"
the evaluation is done using integer computations (modulo 2^b, where b is the number of bits used),if
outtype="double"
the evaluation is done using floating point computations.The default value is
outtype="native"
.For arrays of booleans,
if
outtype="native"
the evaluation is done using boolean computations ( + is replaced by |),if
outtype="double"
the evaluation is done using floating point computations (%t values are replaced by 1 and %f values by 0).The default value is
outtype="double"
.
This function applies with identical rules to sparse matrices |
Examples
See also
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