# Symbols:H

### hecto-

- $\mathrm h$

The Système Internationale d'Unités symbol for the metric scaling prefix **hecto**, denoting $10^{\, 2 }$, is $\mathrm { h }$.

Its $\LaTeX$ code is `\mathrm {h}`

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### Celestial Altitude

- $h$

Let $X$ be a point on the celestial sphere.

The **(celestial) altitude** of $X$ is defined as the angle subtended by the the arc of the vertical circle through $X$ between the celestial horizon and $X$ itself.

It is usually denoted by $h$.

### Subgroup

- $H$

Frequently used to represent a general subgroup of a given group $G$.

### Function

- $\map h x$

The letter $h$, along with $f$ and $g$, is frequently used to denote a general mapping or function.

The $\LaTeX$ code for \(\map h x\) is `\map h x`

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### Hectometre

- $\mathrm {hm}$

The symbol for the **hectometre** is $\mathrm {hm}$:

Its $\LaTeX$ code is `\mathrm {hm}`

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### Heaviside Step Function

- $\map H x$

The symbol used to denote the Heaviside step function is sometimes seen as $\map H x$.

The $\LaTeX$ code for \(\map H x\) is `\map H x`

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### Harmonic Numbers

- $H_n$

The **harmonic numbers** are denoted $H_n$ and are defined for positive integers $n$:

- $\ds \forall n \in \Z, n \ge 0: H_n = \sum_{k \mathop = 1}^n \frac 1 k$

The $\LaTeX$ code for \(H_n\) is `H_n`

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### General Harmonic Numbers

- $H_n^{\paren r} $

Let $r \in \R_{>0}$.

For $n \in \N_{> 0}$ the **Harmonic numbers order $r$** are defined as follows:

- $\ds H_n^{\paren r} = \sum_{k \mathop = 1}^n \frac 1 {k^r}$

The $\LaTeX$ code for \(H_n^{\paren r}\) is `H_n^{\paren r}`

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### Magnetic Field Strength

- $\mathbf H$

The usual symbol used to denote **magnetic field strength** is $\mathbf H$.

Its $\LaTeX$ code is `\mathbf H`

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### Set of Quaternions

- $\Bbb H$

The set of quaternions.

The $\LaTeX$ code for \(\mathbb H\) is `\mathbb H`

or `\Bbb H`

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### Null Hypothesis

- $H_0$

Used to denote the **null hypothesis**:

In the context of a **hypothesis test**, the **null hypothesis**, usually denoted $H_0$, is the **hypothesis** which has been proposed for investigation.

The $\LaTeX$ code for \(H_0\) is `H_0`

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### Alternative Hypothesis

- $H_1$

Used to denote the **alternative hypothesis**:

In the context of a **hypothesis test**, the **alternative hypothesis**, usually denoted $H_1$, is the **hypothesis** which is to be accepted if the **null hypothesis** is demonstrated not to hold.

The $\LaTeX$ code for \(H_1\) is `H_1`

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### Hour Angle

- $\mathrm {HA}$

Used as an abbreviation and to denote the hour angle. Definition:Hour Angle

The $\LaTeX$ code for \(\mathrm {HA}\) is `\mathrm {HA}`

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### Hertz

- $\mathrm {Hz}$

The symbol for the **hertz** is $\mathrm {Hz}$.

Its $\LaTeX$ code is `\mathrm {Hz}`

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### Henry

- $\mathrm H$

The symbol for the **henry** is $\mathrm H$.

Its $\LaTeX$ code is `\mathrm H`

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