Modular inverse: Difference between revisions

=={{header|Lambdatalk}}==

{{trans|Phix}}

<syntaxhighlight lang="scheme">

{def mulinv

{def mulinv.loop

{lambda {:t :nt :r :nr}

{if {not {= :nr 0}}

then {mulinv.loop :nt

{- :t {* {floor {/ :r :nr}} :nt}}

:nr

{- :r {* {floor {/ :r :nr}} :nr}} }

else {cons :t :r} }}}

{lambda {:a :n}

{let { {:a :a} {:n :n}

{:cons {mulinv.loop 0

1

{if {< :n 0} then {- :n} else :n}

{if {< :a 0} then {- :n {% {- :a} :n}} else :a}}}

} {if {> {cdr :cons} 1}

then not invertible

else {if {< {car :cons} 0}

then {+ {car :cons} :n}

else {car :cons} }}}}}

-> mulinv

{mulinv 42 2017}

-> 1969

{mulinv 40 1}

-> 0

{mulinv 52 -217}

-> 96

{mulinv -486 217}

-> 121

{mulinv 40 218}

-> not invertible

</syntaxhighlight>