product of array elements
y=prod(x) y=prod(x,orientation) y=prod(x,outtype) y=prod(x,orientation,outtype)
an array of reals, complex, booleans, polynomials or rational fractions.
it can be either
a string with possible values "*"
, "r"
,
"c"
or "m"
a number with positive integer value
a string with possible values "native"
or "double"
.
scalar or array
For an array x
,
y=prod(x)
returns in the scalar y
the
product of all the elements of x
.
y=prod(x,orientation)
returns in
y
the product of x
along the
dimension given by orientation
:
if orientation
is equal to 1 or "r" then
or
if orientation
is equal to 2 or "c" then:
or
if orientation
is equal to n then
y=prod(x,"*")
is equivalent to y=prod(x)
y=prod(x,"m")
is equivalent to
y=prod(x,orientation)
where
orientation
is the index of the
first dimension of x
that is greater than 1.
The outtype
argument rules the way the product 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 option is used for
Matlab compatibility.
![]() | This function applies with identical rules to sparse matrices. |