Created attachment 156214 [details]
odt file

 When converting from LaTeX (a.tex) to LibreOffice Writer (a.odt): resulting .odt displays only first letter of trigonometric functions (odt.png).
 But pdflatex produces correct result (pdf.png).

Created attachment 156216 [details]
scrennshot of odt document

Created attachment 156217 [details]
scrennshot of pdf document

(In reply to Valdas from comment #2)
>  When converting from LaTeX (a.tex) to LibreOffice Writer (a.odt)

you omitted every possible detail on *how* do you convert?

Sorry, I used PanDoc for that:

pandoc -f latex -t odt -o a.odt a.tex 

pandoc -v:
pandoc 2.8.0.1
Compiled with pandoc-types 1.20, texmath 0.12, skylighting 0.8.3

(In reply to Valdas from comment #6)

Something unrelated to LibreOffice (LibreOffice does not have an import filter for tex). Please file a bug against PanDoc.

PanDoc used for conversion from tex to odt. Resulting odt has converted equation in its native format where trigonometric function has full name (from internal "content.xml" file):

<math display="block" xmlns="http://www.w3.org/1998/Math/MathML"><mrow><msub><mi>x</mi><mn>1</mn></msub><mo>=</mo><msub><mi>l</mi><mn>1</mn></msub><mo>sin</mo><mrow><mo stretchy="true" form="prefix">(</mo><msub><mi>θ</mi><mn>1</mn></msub><mrow><mo stretchy="true" form="prefix">(</mo><mi>t</mi><mo stretchy="true" form="postfix">)</mo></mrow><mo stretchy="true" form="postfix">)</mo></mrow></mrow></math>

But in Libreoffice name appears truncated.

(In reply to Valdas from comment #8)

Exactly. The MathML generated by PanDoc is wrong:

> <?xml version='1.0' ?>
> <math display="block" xmlns="http://www.w3.org/1998/Math/MathML">
>     <mrow>
>         <msub>
>             <mi>x</mi>
>             <mn>1</mn>
>         </msub>
>         <mo>=</mo>
>         <msub>
>             <mi>l</mi>
>             <mn>1</mn>
>         </msub>
>         <mo>sin</mo>
>         <mrow>
>             <mo stretchy="true" form="prefix">(</mo>
>             <msub>
>                 <mi>θ</mi>
>                 <mn>1</mn>
>             </msub>
>             <mrow>
>                 <mo stretchy="true" form="prefix">(</mo>
>                 <mi>t</mi>
>                 <mo stretchy="true" form="postfix">)</mo>
>             </mrow>
>             <mo stretchy="true" form="postfix">)</mo>
>         </mrow>
>     </mrow>
> </math>

Note that "mo" in "<mo>sin</mo>", which is defining "mathematical operator" like "+". But sin is function name, and needs to be in <mi>...</mi>.