# SCALAR_VECTOR_MUL

The SCALAR_VECTOR_MUL function multiples each element in a vector with a scalar value. The function returns a vector.

## Syntax

SCALAR_VECTOR_MUL(scalar_value, vector_expression)

## Arguments

• scalar_value: A scalar value.

• vector_expression: An expression that evaluates to a vector. Vectors can be stored in SingleStore using the native VECTOR type (Vector Type) or the BLOB type (BLOB Types). SingleStore recommends using the VECTOR type when possible.

## Return Type

The function returns the type of the second argument.

## Using SCALAR_VECTOR_MUL with the VECTOR Data Type

### Example 1 - Vector with F32 Element Type

First create a table of vectors of length 4 using the VECTOR data type and insert data into that table.

CREATE TABLE vectors (id int, vec VECTOR(4) not null);
INSERT INTO vectors VALUES (1, '[0.45, 0.55, 0.495, 0.5]');
INSERT INTO vectors VALUES (2, '[0.1, 0.8, 0.2, 0.555]');
INSERT INTO vectors VALUES (3, '[-0.5, -0.03, -0.1, 0.86]');
INSERT INTO vectors VALUES (4, '[0.5, 0.3, 0.807, 0.1]');

Note

The default element type for Vector Type is 32-bit floating point (F32). The Vector Type supports other element types, including integer types, as described in the Vector Type documentation.

The following SQL multiplies each of those vectors by the scalar number 10.

SELECT id, SCALAR_VECTOR_MUL(10, vec)
FROM vectors
ORDER BY id;
+------+---------------------------------+
| id   | SCALAR_VECTOR_MUL(10, vec)      |
+------+---------------------------------+
|    1 | [4.5,5.5,4.94999981,5]          |
|    2 | [1,8,2,5.55000019]              |
|    3 | [-5,-0.299999982,-1,8.60000038] |
|    4 | [5,3,8.06999969,1]              |
+------+---------------------------------+

### Example 2 - Vector with I16 Element Type

This example shows how to use SCALAR_VECTOR_MUL with a VECTOR with an element type of 16-bit integer (I16).

CREATE TABLE vectors_i16(id INT, vec VECTOR(3, I16));
INSERT INTO vectors_i16 VALUES(1, '[1, 2, 3]');
INSERT INTO vectors_i16 VALUES(2, '[4, 5, 6]');
INSERT INTO vectors_i16 VALUES(3, '[1, 4, 8]');

The following SQL multiplies each of the vectors in that table by the scalar number 10.

SELECT id, SCALAR_VECTOR_MUL(10, vec)
FROM vectors_i16
ORDER BY id;
+------+----------------------------+
| id   | SCALAR_VECTOR_MUL(10, vec) |
+------+----------------------------+
|    1 | [10,20,30]                 |
|    2 | [40,50,60]                 |
|    3 | [10,40,80]                 |
+------+----------------------------+

## Using SCALAR_VECTOR_MUL with Vectors as BLOBs

The following examples and descriptions show the use of SCALAR_VECTOR_MUL to multiply the a vector by a scalar when the elements of the vector are stored as a BLOB.

### Example 1 - BLOB Argument

Create a table with a column of type BLOB to store the vectors. The second column in this table, with column name vec and type BLOB, will store the vectors. This example demonstrates storing vector data using BLOBs, hence the column of type BLOB named vec.

Then use the JSON_ARRAY_PACK built-in function to easily insert properly formatted vectors.

CREATE TABLE vectors_b (id int, vec BLOB not null);
INSERT INTO vectors_b VALUES (1, JSON_ARRAY_PACK('[0.1, 0.8, 0.2, 0.555]'));
INSERT INTO vectors_b VALUES (2, JSON_ARRAY_PACK('[0.45, 0.55, 0.495, 0.5]'));

The following query multiples the vectors in the vectors_b table by 10 and uses JSON_ARRAY_UNPACK to see the results in JSON format.

SELECT id, JSON_ARRAY_UNPACK(SCALAR_VECTOR_MUL(10, vec)) as scalar_mul
FROM vectors_b
ORDER BY id;
+------+------------------------+
| id   | scalar_mul             |
+------+------------------------+
|    1 | [1,8,2,5.55000019]     |
|    2 | [4.5,5.5,4.94999981,5] |
+------+------------------------+

JSON_ARRAY_UNPACK was used here to output the vectors in readable format because VECTOR_SORT returns a BLOB when its second argument is a BLOB.

The following query multiples the vectors in the vectors_b table by 10 and uses HEX to view the results in hexadecimal format.

SELECT id, HEX(SCALAR_VECTOR_MUL(10, vec)) as scalar_mul
FROM vectors_b
ORDER BY id;
+------+----------------------------------+
| id   | scalar_mul                       |
+------+----------------------------------+
|    1 | 0000803F00000041000000409A99B140 |
|    2 | 000090400000B04066669E400000A040 |
+------+----------------------------------+

### Using Suffixes for Other Element Types with BLOBs

The default element type for vector storage and processing is 32-bit floating point (F32). However, other element types are supported.

You can specify the datatype of the vector elements to be used in the operation by adding a suffix to the function. All operations are done using the specified datatype. Omitting the suffix from the function is equivalent to suffixing it with _F32.

When using a suffix, the return type will be the type of the suffix.

Note

The functions with suffixes do not work with the VECTOR type.

The following table lists the suffixes and their data type.

Suffix

Data Type

_I8

8-bit signed integer

_I16

16-bit signed integer

_I32

32-bit signed integer

_I64

64-bit signed integer

_F32

32-bit floating-point number (IEEE standard format)

_F64

64-bit floating-point number (IEEE standard format)

### Example 2 - BLOBs with 16-bit Integers

Below is an example of using JSON_ARRAY_PACK and SCALAR_VECTOR_MUL with 16-bit signed integers.

First create a table of vectors stored as 16-bit integers. Note the use of the _I16 suffix on JSON_ARRAY_PACK.

CREATE TABLE vectors_b_i (id int, vec BLOB not null);
INSERT INTO vectors_b_i VALUES (1, JSON_ARRAY_PACK_I16('[1, 3, 2, 5]'));
INSERT INTO vectors_b_i VALUES(2, JSON_ARRAY_PACK_I16('[23, 4, 1, 8]'));

This following query multiplies the vectors in the vectors_b_i table by the scalar 10.

SELECT id, JSON_ARRAY_UNPACK_I16(SCALAR_VECTOR_MUL_I16(10, vec)) AS scalar_mul
FROM vectors_b_i
ORDER BY id;
+------+-----------------+
| id   | scalar_mul      |
+------+-----------------+
|    1 | [10,30,20,50]  |
|    2 | [230,40,10,80] |
+------+-----------------+

Note

Be sure that the suffixes you use to pack the vector data match the suffixes you use to unpack the data and the suffixes you use on functions to process that data.

### Formatting Binary Vector Data for BLOBs

When using the BLOB type for vector operations, vector data can be formatted using JSON_ARRAY_PACK. If your vector data is already in a packed binary format, you can load that data into the BLOBs. The data must be encoded as a BLOB containing packed numbers in little-endian byte order. Vectors stored as BLOBs can be of any length; however, the input blob length must be divisible by the size of the packed vector elements (1, 2, 4 , or 8 bytes, depending on the vector element).

## Troubleshooting

Should you receive an unexpected NULL value or values in the results, check the order of the arguments. The SCALAR_VECTOR_MUL function returns NULL if the order of arguments is reversed.

Using the vectors table created above, the following query reverses the order of the arguments, putting the VECTOR first and the scalar value (10) second. The result is four NULL values as is expected when the order of arguments is reversed.

SELECT id, SCALAR_VECTOR_MUL(vec, 10)
FROM vectors
ORDER BY id;
+------+----------------------------+
| id   | SCALAR_VECTOR_MUL(vec, 10) |
+------+----------------------------+
|    1 | NULL                       |
|    2 | NULL                       |
|    3 | NULL                       |
|    4 | NULL                       |
+------+----------------------------+