Arithmetic-geometric mean: Difference between revisions

=={{header|Lambdatalk}}==

<syntaxhighlight lang="Scheme">

{def agm

{def agm.r

{lambda {:an :gn :tol}

{if {> {abs {- :an :gn}} :tol}

then {agm.r {/ {+ :an :gn} 2} {sqrt {* :an :gn}} :tol}

else :an }}}

{lambda {:a0 :g0}

{agm.r {/ {+ :a0 :g0} 2} {sqrt {* :a0 :g0}} 1e-15}}}

-> agm

{agm 1 {/ 1 {sqrt 2}}}

-> 0.8472130847939792

Using the lib_BN library we compute 70 digits

{def AGM

{def AGM.r

{lambda {:an :gn :tol}

{if {= {BN.compare {BN.abs {BN.- :an :gn}} :tol} 1}

then {AGM.r {BN./ {BN.+ :an :gn} 2}

{BN.sqrt {BN.* :an :gn}}

:tol}

else :an }}}

{lambda {:a0 :g0}

{AGM.r {BN./ {BN.+ :a0 :g0} 2}

{BN.sqrt {BN.* :a0 :g0}}

{BN./ 1 {BN.pow 10 45}}}}}

-> AGM

{BN.DEC 70}

-> 70 digits

{AGM 1 {BN./ 1 {BN.sqrt 2}}}

-> 0.8472130847939790866064991234821916364814459103269421850605793726597339

</syntaxhighlight>