2 OpenMath functionality in GAP

After loading the share package the following operations are available.

OMPrint( obj ) F

OMPrint writes the XML OpenMath encoding of GAP object obj to the standard output.

gap> g := Group((1,2,3));;
gap> OMPrint(g);
<OMOBJ>
	<OMA>
		<OMS cd="group1" name="Group"/>
		<OMA>
			<OMS cd="permut1" name="Permutation"/>
			<OMI> 2</OMI>
			<OMI> 3</OMI>
			<OMI> 1</OMI>
		</OMA>
	</OMA>
</OMOBJ>

OMGetObject( stream ) F

stream is an input stream with an OpenMath object on it. OMGetObject takes precisely one object off stream and returns it as a GAP object.

This may be used to retrieve objects from a file, for example:

gap> stream := InputTextFile(test3.omt");;
gap> OMGetObject(stream);
912873912381273891

or it can be used to retrieve them from standard input - one may paste an OpenMath object direcly into standard input after issuing GAP with the following commands:

gap> stream := InputTextUser();;
gap> g := OMGetObject(stream);

OMPutObject( stream, obj ) F

OMPutObject writes the XML OpenMath encoding of the GAP object obj to output stream stream.

gap> g := [[1,2],[1,0]];;
gap> t := "";
""
gap> s := OutputTextString(t, true);;
gap> OMPutObject(s, g);
gap> CloseStream(s);
gap> Print(t);
<OMOBJ>
	<OMA>
		<OMS cd="linalg1" name="matrix"/>
		<OMA>
			<OMS cd="linalg1" name="matrixrow"/>
			<OMI> 1</OMI>
			<OMI> 2</OMI>
		</OMA>
		<OMA>
			<OMS cd="linalg1" name="matrixrow"/>
			<OMI> 1</OMI>
			<OMI> 0</OMI>
		</OMA>
	</OMA>
</OMOBJ>

OMTest( obj ) F

Converts obj to OpenMath and back. Returns true iff obj is unchanged (as a GAP object) by this operation. The OpenMath standard does not stipulate that converting to and from OpenMath should be the identity function so this is a useful diagnostic tool.

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OpenMath manual
May 2002