# prod

product of array elements

### Syntax

y=prod(x) y=prod(x,orientation) y=prod(x,outtype) y=prod(x,orientation,outtype)

### Arguments

- x
an array of reals, complex, booleans, polynomials or rational fractions.

- orientation
it can be either

a string with possible values

`"*"`

,`"r"`

,`"c"`

or`"m"`

a number with positive integer value

- outtype
a string with possible values

`"native"`

or`"double"`

.- y
scalar or array

### Description

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" thenor

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 . |

### Examples

A=[1,2;3,4]; prod(A) prod(A,1) I=uint8([2 95 103;254 9 0]) prod(I) //native evaluation prod(I,"double") prod(I,2,"double") s=poly(0,"s"); P=[s,%i+s;s^2,1]; prod(P), prod(P,2) B=[%t %t %f %f]; prod(B) //evaluation in float prod(B,"native") //similar to and(B)

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