---
name: "ddot.f"
section: "3"
platform: "linux"
package: "lapack-doc"
version: "3.12.1-2"
release: "Arch Linux 2026-11-01"
platforms: ["linux"]
url: "https://new.carta.tech/ddot.f"
---

# ddot.f(3)

## NAME

BLAS/SRC/ddot.f

## SYNOPSIS

### Functions/Subroutines

double precision function **ddot** (n, dx, incx, dy, incy)\
 **DDOT**

## Function/Subroutine Documentation

### double precision function ddot (integer n, double precision, dimension(\*) dx, integer incx, double precision, dimension(\*) dy, integer incy)

**DDOT**

**Purpose:**

```
!>
!>    DDOT forms the dot product of two vectors.
!>    uses unrolled loops for increments equal to one.
!>
```

**Parameters**

*N*

```
!>          N is INTEGER
!>         number of elements in input vector(s)
!>
```

*DX*

```
!>          DX is DOUBLE PRECISION array, dimension ( 1 + ( N - 1 )*abs( INCX ) )
!>
```

*INCX*

```
!>          INCX is INTEGER
!>         storage spacing between elements of DX
!>
```

*DY*

```
!>          DY is DOUBLE PRECISION array, dimension ( 1 + ( N - 1 )*abs( INCY ) )
!>
```

*INCY*

```
!>          INCY is INTEGER
!>         storage spacing between elements of DY
!>
```

**Author**

Univ. of Tennessee

Univ. of California Berkeley

Univ. of Colorado Denver

NAG Ltd.

**Further Details:**

```
!>
!>     jack dongarra, linpack, 3/11/78.
!>     modified 12/3/93, array(1) declarations changed to array(*)
!>
```

Definition at line **81** of file **ddot.f**.

## Author

Generated automatically by Doxygen for LAPACK from the source code.