---
title: "A-B (DMATH)"
slug: "dmathfunction-4"
updated: 2021-11-02T09:17:14Z
published: 2021-11-02T09:17:14Z
canonical: "docs.datajet.app/dmathfunction-4"
---

> ## Documentation Index
> Fetch the complete documentation index at: https://docs.datajet.app/llms.txt
> Use this file to discover all available pages before exploring further.

# A-B (DMATH)

## DMath: A-B

## Subtracts the value of B from the value of A

## Purpose

Use this function to:

- Calculate the difference between subtrahend and minuend.
- Subtract the value of one field from another
- Decrement a column by a fixed value

## Return Value

| Property | Value |
| --- | --- |
| **FieldType** | Double |
| **FieldSize** | Low / Med / High / Continuous |
| **DataType** | Discrete / Continuous |
| **DataSize** | Short / Integer / LongInteger / Double |

```shell
Example Return Value: X*.XXXXXX....-X*.XXXXX

e.g.  21.000000, 98754654.123456, -5.000000, -654.320000
```

![](https://cdn.document360.io/73b6469b-c1e4-47e9-aa65-986c8ebd17ca/Images/Documentation/DMATH_AminusB_Sample.PNG)

## Parameters

| Parameter | JSON | Description |
| --- | --- | --- |
| **Table** | “targetTable”: “MyTableName” | The target table on which the new field will be created |
| **Filter** | “dataset”: {DataSet_JSON} | Optional. If a filter is applied, records not in the filter recordset will be returned as null. |
| **Math** **Function** | “p1”: “” |  |
| **A** | “p2”: “NumericFieldName” “p2”: “#N*.N*” | Required. The minuend. *Supports:* - **DataType:** Discrete / Continuous - **Field Type:** Integer, Double - **Fixed Value:** #N* e.g. #201596, #-87 - **Fixed Value:** #N*.N* e.g. #201596.05, #-87.98 |
| **B** | “p3”: “NumericFieldName” “p3”: “#N*.N*” | Required. The subtrahend. *Supports:* - **DataType:** Discrete / Continuous - **Field Type:** Integer, Double - **Fixed Value:** #N* e.g. #201596, #-87 - **Fixed Value:** #N*.N* e.g. #201596.05, #-87.98 |
| **Treat Null as Zero** | "nullIsZero": true "nullIsZero": false | True/False. Default = False If true, then any null values in the input fields will be treated as if they have a value of 0. |

## JSON Sample

![](https://cdn.document360.io/73b6469b-c1e4-47e9-aa65-986c8ebd17ca/Images/Documentation/DMATH_AminusB_JSON.PNG)

## Usage Notes

See Also:

- Mathematical Expression Field
- LMATH A-B
- [DMATH Overview](https://datajet.document360.io/docs/dmathfunction-1)

## Example

| Example | Details |
| --- | --- |
| **Description** | Reduce percentage by fixed amount |
| **Input** | - Table: = [transactopms] - Filter: = [No Filter] - Function: = DMath - **Math Function** **= A-B** - A:= [transactions].[percent] - B:= #0.25 - Name: = percent_lessquarter |
| **Sample** | ![](https://cdn.document360.io/73b6469b-c1e4-47e9-aa65-986c8ebd17ca/Images/Documentation/DMATH_AminusB_Example.PNG) |