---
name: "dsdot.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/dsdot.f"
---

# dsdot.f(3)

## NAME

BLAS/SRC/dsdot.f

## SYNOPSIS

### Functions/Subroutines

double precision function **dsdot** (n, sx, incx, sy, incy)\
 **DSDOT**

## Function/Subroutine Documentation

### double precision function dsdot (integer n, real, dimension(\*) sx, integer incx, real, dimension(\*) sy, integer incy)

**DSDOT**

**Purpose:**

```
!>
!> Compute the inner product of two vectors with extended
!> precision accumulation and result.
!>
!> Returns D.P. dot product accumulated in D.P., for S.P. SX and SY
!> DSDOT = sum for I = 0 to N-1 of  SX(LX+I*INCX) * SY(LY+I*INCY),
!> where LX = 1 if INCX .GE. 0, else LX = 1+(1-N)*INCX, and LY is
!> defined in a similar way using INCY.
!>
```

**Parameters**

*N*

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

*SX*

```
!>          SX is REAL array, dimension(N)
!>         single precision vector with N elements
!>
```

*INCX*

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

*SY*

```
!>          SY is REAL array, dimension(N)
!>         single precision vector with N elements
!>
```

*INCY*

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

**Returns**

DSDOT

```
!>          DSDOT is DOUBLE PRECISION
!>         DSDOT  double precision dot product (zero if N.LE.0)
!>
```

**Author**

Univ. of Tennessee

Univ. of California Berkeley

Univ. of Colorado Denver

NAG Ltd.

**Further Details:**

```
!>
```

**References:**

```
!>
!>
!>  C. L. Lawson, R. J. Hanson, D. R. Kincaid and F. T.
!>  Krogh, Basic linear algebra subprograms for Fortran
!>  usage, Algorithm No. 539, Transactions on Mathematical
!>  Software 5, 3 (September 1979), pp. 308-323.
!>
!>  REVISION HISTORY  (YYMMDD)
!>
!>  791001  DATE WRITTEN
!>  890831  Modified array declarations.  (WRB)
!>  890831  REVISION DATE from Version 3.2
!>  891214  Prologue converted to Version 4.0 format.  (BAB)
!>  920310  Corrected definition of LX in DESCRIPTION.  (WRB)
!>  920501  Reformatted the REFERENCES section.  (WRB)
!>  070118  Reformat to LAPACK style (JL)
!>
```

Definition at line **118** of file **dsdot.f**.

## Author

Generated automatically by Doxygen for LAPACK from the source code.