U+210D DOUBLESTRUCK CAPITAL H
U+210D was added to Unicode in version 1.1 (1993). It belongs to the block
This character is a Uppercase Letter and is commonly used, that is, in no specific script.
The glyph is a Font composition of the glyph
The Wikipedia has the following information about this codepoint:
In mathematics, the quaternion number system extends the complex numbers. Quaternions were first described by the Irish mathematician William Rowan Hamilton in 1843 and applied to mechanics in threedimensional space. Hamilton defined a quaternion as the quotient of two directed lines in a threedimensional space, or, equivalently, as the quotient of two vectors. Multiplication of quaternions is noncommutative.
Quaternions are generally represented in the form
 a + b i + c j + d k {displaystyle a+b mathbf {i} +c mathbf {j} +d mathbf {k} }
where a, b, c, and d are real numbers; and i, j, and k are the basic quaternions.
Quaternions are used in pure mathematics, but also have practical uses in applied mathematics, particularly for calculations involving threedimensional rotations, such as in threedimensional computer graphics, computer vision, and crystallographic texture analysis. They can be used alongside other methods of rotation, such as Euler angles and rotation matrices, or as an alternative to them, depending on the application.
In modern mathematical language, quaternions form a fourdimensional associative normed division algebra over the real numbers, and therefore a ring, being both a division ring and a domain. The algebra of quaternions is often denoted by H (for Hamilton), or in blackboard bold by H . {displaystyle mathbb {H} .} It can also be given by the Clifford algebra classifications Cl 0 , 2 ( R ) ≅ Cl 3 , 0 + ( R ) . {displaystyle operatorname {Cl} _{0,2}(mathbb {R} )cong operatorname {Cl} _{3,0}^{+}(mathbb {R} ).} In fact, it was the first noncommutative division algebra to be discovered.
According to the Frobenius theorem, the algebra H {displaystyle mathbb {H} } is one of only two finitedimensional division rings containing a proper subring isomorphic to the real numbers; the other being the complex numbers. These rings are also Euclidean Hurwitz algebras, of which the quaternions are the largest associative algebra (and hence the largest ring). Further extending the quaternions yields the nonassociative octonions, which is the last normed division algebra over the real numbers. (The sedenions, the extension of the octonions, have zero divisors and so cannot be a normed division algebra.)
The unit quaternions can be thought of as a choice of a group structure on the 3sphere S^{3} that gives the group Spin(3), which is isomorphic to SU(2) and also to the universal cover of SO(3).
Representations
System  Representation 

Nº  8461 
UTF8  E2 84 8D 
UTF16  21 0D 
UTF32  00 00 21 0D 
URLQuoted  %E2%84%8D 
HTMLEscape  ℍ 
Wrong windows1252 Mojibake  â 
HTMLEscape  ℍ 
HTMLEscape  ℍ 
L^{A}T_{E}X  \mathbb{H} 
Related Characters
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Complete Record
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1.1 (1993)  
DOUBLESTRUCK CAPITAL H  
DOUBLESTRUCK H  
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