The eqn function produces output which is suitable for printing the input expression expr with a troff/eqn processor. It knows how to format integrals, limits, sums, products and matrices.

The mathematical format is taken, in general, from the CRC handbook or the Handbook of Mathematical functions.

The functions sum, product, int, diff, limit, and log are aliased by Sum, Product, Int, Diff, Limit, and Log, so that these can be used to prevent evaluation by Maple.

User-defined function printing can be interfaced by including a procedure `eqn/function-name`.

Note eqn will not produce .EQ or .EN lines in the output file.

The function eqn produces output as a side-effect, and returns NULL as the function value. Therefore the ditto commands, % and %%, will not recall the output of an eqn command.

{{{  "x"  sup 2 }^+^{  "y"  sup 2 }}~~=~~{  "z"  sup 2 }}

{{int  { {( {{  "x"  sup 2 }^+^1 } )} sup -1 }~d  "x" }~~=~~{arctan (
 "x" )}}