this is my tree:

`+`(`-`(`-`(X2,`*`(`*`(`*`(`*`(X4,X1),`*`(X4,X3)),X2),`-`(`-`(`/`(X1,X3),`*`(`*`(`*`(`/`(0.25382,X3),`+`(X2,X2)),X4),X2)),`*`(X4,`-`(X2,`*`(`*`(`*`(`-`(0.66077,`+`(`*`(X1,`*`(X3,0.80412)),`-`(`*`(`*`(X4,X4),X2),`*`(X3,`/`(X4,X2))))),`*`(`*`(0.78443,X2),X3)),X2),`-`(`-`(`/`(X1,X3),`+`(X3,X4)),`*`(`*`(`*`(`-`(`-`(X2,`*`(`*`(`*`(`*`(X4,`+`(X1,X3)),`*`(X4,X3)),X2),`-`(`/`(`-`(X4,`-`(0.5,`+`(X2,X2))),`-`(X1,X2)),X1))),X1),`*`(X3,`*`(X4,X1))),X2),`-`(`-`(`/`(X1,X3),`*`(X1,X1)),`*`(`*`(`*`(`-`(0.66077,`+`(`*`(X1,`*`(X3,0.80412)),`-`(`*`(`*`(X4,X4),0.79187),`*`(`*`(`*`(`*`(`-`(X3,X1),`*`(X3,X1)),X2),X4),`/`(X4,X2))))),`*`(`*`(0.78443,X2),X3)),X2),`-`(`-`(`/`(X1,X3),0.61363),`*`(`*`(`*`(`-`(`-`(X2,`*`(`*`(`*`(`*`(X4,+(X1,X3)),`*`(X4,X3)),X2),`-`(`-`(`/`(0.78443,X3),`*`(`*`(`-

`(`+`(X3,`*`(0.80628,0.66077)),X1),`*`(0.6734,`-`(X2,0.5))),X2)),`*`(X4,`-`(X2,`*`(`*`(`*`(`*`(X4,X1),`*`(`*`(0

.78443,X4),X3)),X2),`-`(`-`(`+`(X2,X2),`*`(X1,X2)),X3))))))),X1),`*`(X3,`*`(X4,X1))),X2),`-`(`-`(`/`(X1,X3),`-`(X4,`-`(0.5,`+`(X2,X2)))),X1))))))))))))),X1),`*`(0.78443,X3));

when i run it on maple, i've got this error message:

Error, missing operation

what should i do then?

thank you, it works

is there a way to make it more simplify?