I am trying to write arithmetic, geometric and harmonic mean functions in openscad. It appears I need to use recursion ( Here is my program: echo(sum([1,2,3])); function sum(values,i=0)=( (i==len(values)) ? values[i] : values[i] + sum(values, //f, i+1) ); The output should be 6. with the comment in line 5, the output is undef, if you uncomment the "f," you get 5 errors, not 3, which means there are too many calls. Can anyone give me some help? I took a look at the WikiBook, but it didnt help me much: https://en.wikibooks.org/w/index.php?title=OpenSCAD_User_ Manual/User-Defined_Functions_and_Modules&stable=0#Recursive_functions Or if you have already written the functions I want (product, sum, aritmentic mean, harmonic mean, and geometric mean) of a list of values, send me those. Thanks, Ari M Diacou, Metis Industries

When i == len(values) you return values[i] but lists are indexed from 0, so you are try to access one past the end, hence the undef. On 24 February 2017 at 23:10, Ari Diacou <ari.diacou@gmail.com> wrote: > > > I am trying to write arithmetic, geometric and harmonic mean functions in > openscad. > > It appears I need to use recursion ( > > Here is my program: > > echo(sum([1,2,3])); > function sum(values,i=0)=( > (i==len(values)) ? > values[i] : > values[i] + sum(values, //f, > i+1) > ); > > The output should be 6. with the comment in line 5, the output is undef, > if you uncomment the "f," you get 5 errors, not 3, which means there are > too many calls. > > Can anyone give me some help? > > I took a look at the WikiBook, but it didnt help me much: > https://en.wikibooks.org/w/index.php?title=OpenSCAD_User_Man > ual/User-Defined_Functions_and_Modules&stable=0#Recursive_functions > > Or if you have already written the functions I want (product, sum, > aritmentic mean, harmonic mean, and geometric mean) of a list of values, > send me those. > > Thanks, > Ari M Diacou, Metis Industries > > > _______________________________________________ > OpenSCAD mailing list > Discuss@lists.openscad.org > http://lists.openscad.org/mailman/listinfo/discuss_lists.openscad.org > >

Thanks a lot nophead! On Fri, Feb 24, 2017 at 6:18 PM, nop head <nop.head@gmail.com> wrote: > When i == len(values) you return values[i] but lists are indexed from 0, > so you are try to access one past the end, hence the undef. > > > > On 24 February 2017 at 23:10, Ari Diacou <ari.diacou@gmail.com> wrote: > >> >> >> I am trying to write arithmetic, geometric and harmonic mean functions in >> openscad. >> >> It appears I need to use recursion ( >> >> Here is my program: >> >> echo(sum([1,2,3])); >> function sum(values,i=0)=( >> (i==len(values)) ? >> values[i] : >> values[i] + sum(values, //f, >> i+1) >> ); >> >> The output should be 6. with the comment in line 5, the output is undef, >> if you uncomment the "f," you get 5 errors, not 3, which means there are >> too many calls. >> >> Can anyone give me some help? >> >> I took a look at the WikiBook, but it didnt help me much: >> https://en.wikibooks.org/w/index.php?title=OpenSCAD_User_Man >> ual/User-Defined_Functions_and_Modules&stable=0#Recursive_functions >> >> Or if you have already written the functions I want (product, sum, >> aritmentic mean, harmonic mean, and geometric mean) of a list of values, >> send me those. >> >> Thanks, >> Ari M Diacou, Metis Industries >> >> >> _______________________________________________ >> OpenSCAD mailing list >> Discuss@lists.openscad.org >> http://lists.openscad.org/mailman/listinfo/discuss_lists.openscad.org >> >> > > _______________________________________________ > OpenSCAD mailing list > Discuss@lists.openscad.org > http://lists.openscad.org/mailman/listinfo/discuss_lists.openscad.org > >

echo(sum([1,2,3])); function sum(values, i = 0) = i == len(values) ? 0 : values[i] + sum(values, i + 1); Works. On 24 February 2017 at 23:18, nop head <nop.head@gmail.com> wrote: > When i == len(values) you return values[i] but lists are indexed from 0, > so you are try to access one past the end, hence the undef. > > > > On 24 February 2017 at 23:10, Ari Diacou <ari.diacou@gmail.com> wrote: > >> >> >> I am trying to write arithmetic, geometric and harmonic mean functions in >> openscad. >> >> It appears I need to use recursion ( >> >> Here is my program: >> >> echo(sum([1,2,3])); >> function sum(values,i=0)=( >> (i==len(values)) ? >> values[i] : >> values[i] + sum(values, //f, >> i+1) >> ); >> >> The output should be 6. with the comment in line 5, the output is undef, >> if you uncomment the "f," you get 5 errors, not 3, which means there are >> too many calls. >> >> Can anyone give me some help? >> >> I took a look at the WikiBook, but it didnt help me much: >> https://en.wikibooks.org/w/index.php?title=OpenSCAD_User_Man >> ual/User-Defined_Functions_and_Modules&stable=0#Recursive_functions >> >> Or if you have already written the functions I want (product, sum, >> aritmentic mean, harmonic mean, and geometric mean) of a list of values, >> send me those. >> >> Thanks, >> Ari M Diacou, Metis Industries >> >> >> _______________________________________________ >> OpenSCAD mailing list >> Discuss@lists.openscad.org >> http://lists.openscad.org/mailman/listinfo/discuss_lists.openscad.org >> >> >

Nice, I like that format better. On Fri, Feb 24, 2017 at 6:21 PM, nop head <nop.head@gmail.com> wrote: > echo(sum([1,2,3])); > function sum(values, i = 0) = > i == len(values) ? 0 : values[i] + sum(values, i + 1); > > Works. > > On 24 February 2017 at 23:18, nop head <nop.head@gmail.com> wrote: > >> When i == len(values) you return values[i] but lists are indexed from 0, >> so you are try to access one past the end, hence the undef. >> >> >> >> On 24 February 2017 at 23:10, Ari Diacou <ari.diacou@gmail.com> wrote: >> >>> >>> >>> I am trying to write arithmetic, geometric and harmonic mean functions >>> in openscad. >>> >>> It appears I need to use recursion ( >>> >>> Here is my program: >>> >>> echo(sum([1,2,3])); >>> function sum(values,i=0)=( >>> (i==len(values)) ? >>> values[i] : >>> values[i] + sum(values, //f, >>> i+1) >>> ); >>> >>> The output should be 6. with the comment in line 5, the output is undef, >>> if you uncomment the "f," you get 5 errors, not 3, which means there are >>> too many calls. >>> >>> Can anyone give me some help? >>> >>> I took a look at the WikiBook, but it didnt help me much: >>> https://en.wikibooks.org/w/index.php?title=OpenSCAD_User_Man >>> ual/User-Defined_Functions_and_Modules&stable=0#Recursive_functions >>> >>> Or if you have already written the functions I want (product, sum, >>> aritmentic mean, harmonic mean, and geometric mean) of a list of values, >>> send me those. >>> >>> Thanks, >>> Ari M Diacou, Metis Industries >>> >>> >>> _______________________________________________ >>> OpenSCAD mailing list >>> Discuss@lists.openscad.org >>> http://lists.openscad.org/mailman/listinfo/discuss_lists.openscad.org >>> >>> >> > > _______________________________________________ > OpenSCAD mailing list > Discuss@lists.openscad.org > http://lists.openscad.org/mailman/listinfo/discuss_lists.openscad.org > >

echo(sum([1,2,3])); function sum(values, i = 0, sum = 0) = i == len(values) ? sum : sum(values, i + 1, sum + values[i]); Is a better way to do it because it uses tail recursion. I.e. it ends by calling itself. That is optimised to a loop by OpenSCAD, so it doesn't run out of stack. On 24 February 2017 at 23:23, Ari Diacou <ari.diacou@gmail.com> wrote: > Nice, I like that format better. > > On Fri, Feb 24, 2017 at 6:21 PM, nop head <nop.head@gmail.com> wrote: > >> echo(sum([1,2,3])); >> function sum(values, i = 0) = >> i == len(values) ? 0 : values[i] + sum(values, i + 1); >> >> Works. >> >> On 24 February 2017 at 23:18, nop head <nop.head@gmail.com> wrote: >> >>> When i == len(values) you return values[i] but lists are indexed from 0, >>> so you are try to access one past the end, hence the undef. >>> >>> >>> >>> On 24 February 2017 at 23:10, Ari Diacou <ari.diacou@gmail.com> wrote: >>> >>>> >>>> >>>> I am trying to write arithmetic, geometric and harmonic mean functions >>>> in openscad. >>>> >>>> It appears I need to use recursion ( >>>> >>>> Here is my program: >>>> >>>> echo(sum([1,2,3])); >>>> function sum(values,i=0)=( >>>> (i==len(values)) ? >>>> values[i] : >>>> values[i] + sum(values, //f, >>>> i+1) >>>> ); >>>> >>>> The output should be 6. with the comment in line 5, the output is >>>> undef, if you uncomment the "f," you get 5 errors, not 3, which means there >>>> are too many calls. >>>> >>>> Can anyone give me some help? >>>> >>>> I took a look at the WikiBook, but it didnt help me much: >>>> https://en.wikibooks.org/w/index.php?title=OpenSCAD_User_Man >>>> ual/User-Defined_Functions_and_Modules&stable=0#Recursive_functions >>>> >>>> Or if you have already written the functions I want (product, sum, >>>> aritmentic mean, harmonic mean, and geometric mean) of a list of values, >>>> send me those. >>>> >>>> Thanks, >>>> Ari M Diacou, Metis Industries >>>> >>>> >>>> _______________________________________________ >>>> OpenSCAD mailing list >>>> Discuss@lists.openscad.org >>>> http://lists.openscad.org/mailman/listinfo/discuss_lists.openscad.org >>>> >>>> >>> >> >> _______________________________________________ >> OpenSCAD mailing list >> Discuss@lists.openscad.org >> http://lists.openscad.org/mailman/listinfo/discuss_lists.openscad.org >> >> > > _______________________________________________ > OpenSCAD mailing list > Discuss@lists.openscad.org > http://lists.openscad.org/mailman/listinfo/discuss_lists.openscad.org > >

That was the part of the wikibook i didn't understand, although I at least updated the link to the wikipedia article. On Fri, Feb 24, 2017 at 6:25 PM, nop head <nop.head@gmail.com> wrote: > echo(sum([1,2,3])); > > function sum(values, i = 0, sum = 0) = > i == len(values) ? sum : sum(values, i + 1, sum + values[i]); > > Is a better way to do it because it uses tail recursion. I.e. it ends by > calling itself. That is optimised to a loop by OpenSCAD, so it doesn't run > out of stack. > > On 24 February 2017 at 23:23, Ari Diacou <ari.diacou@gmail.com> wrote: > >> Nice, I like that format better. >> >> On Fri, Feb 24, 2017 at 6:21 PM, nop head <nop.head@gmail.com> wrote: >> >>> echo(sum([1,2,3])); >>> function sum(values, i = 0) = >>> i == len(values) ? 0 : values[i] + sum(values, i + 1); >>> >>> Works. >>> >>> On 24 February 2017 at 23:18, nop head <nop.head@gmail.com> wrote: >>> >>>> When i == len(values) you return values[i] but lists are indexed from >>>> 0, so you are try to access one past the end, hence the undef. >>>> >>>> >>>> >>>> On 24 February 2017 at 23:10, Ari Diacou <ari.diacou@gmail.com> wrote: >>>> >>>>> >>>>> >>>>> I am trying to write arithmetic, geometric and harmonic mean functions >>>>> in openscad. >>>>> >>>>> It appears I need to use recursion ( >>>>> >>>>> Here is my program: >>>>> >>>>> echo(sum([1,2,3])); >>>>> function sum(values,i=0)=( >>>>> (i==len(values)) ? >>>>> values[i] : >>>>> values[i] + sum(values, //f, >>>>> i+1) >>>>> ); >>>>> >>>>> The output should be 6. with the comment in line 5, the output is >>>>> undef, if you uncomment the "f," you get 5 errors, not 3, which means there >>>>> are too many calls. >>>>> >>>>> Can anyone give me some help? >>>>> >>>>> I took a look at the WikiBook, but it didnt help me much: >>>>> https://en.wikibooks.org/w/index.php?title=OpenSCAD_User_Man >>>>> ual/User-Defined_Functions_and_Modules&stable=0#Recursive_functions >>>>> >>>>> Or if you have already written the functions I want (product, sum, >>>>> aritmentic mean, harmonic mean, and geometric mean) of a list of values, >>>>> send me those. >>>>> >>>>> Thanks, >>>>> Ari M Diacou, Metis Industries >>>>> >>>>> >>>>> _______________________________________________ >>>>> OpenSCAD mailing list >>>>> Discuss@lists.openscad.org >>>>> http://lists.openscad.org/mailman/listinfo/discuss_lists.openscad.org >>>>> >>>>> >>>> >>> >>> _______________________________________________ >>> OpenSCAD mailing list >>> Discuss@lists.openscad.org >>> http://lists.openscad.org/mailman/listinfo/discuss_lists.openscad.org >>> >>> >> >> _______________________________________________ >> OpenSCAD mailing list >> Discuss@lists.openscad.org >> http://lists.openscad.org/mailman/listinfo/discuss_lists.openscad.org >> >> > > _______________________________________________ > OpenSCAD mailing list > Discuss@lists.openscad.org > http://lists.openscad.org/mailman/listinfo/discuss_lists.openscad.org > >

The difference is the previous version has to add values[i] after it calls itself, so it has to actually recurse. When the tail is just a call to itself with nothing to do afterwards it can be made into a loop. On 24 February 2017 at 23:28, Ari Diacou <ari.diacou@gmail.com> wrote: > That was the part of the wikibook i didn't understand, although I at least > updated the link to the wikipedia article. > > On Fri, Feb 24, 2017 at 6:25 PM, nop head <nop.head@gmail.com> wrote: > >> echo(sum([1,2,3])); >> >> function sum(values, i = 0, sum = 0) = >> i == len(values) ? sum : sum(values, i + 1, sum + values[i]); >> >> Is a better way to do it because it uses tail recursion. I.e. it ends by >> calling itself. That is optimised to a loop by OpenSCAD, so it doesn't run >> out of stack. >> >> On 24 February 2017 at 23:23, Ari Diacou <ari.diacou@gmail.com> wrote: >> >>> Nice, I like that format better. >>> >>> On Fri, Feb 24, 2017 at 6:21 PM, nop head <nop.head@gmail.com> wrote: >>> >>>> echo(sum([1,2,3])); >>>> function sum(values, i = 0) = >>>> i == len(values) ? 0 : values[i] + sum(values, i + 1); >>>> >>>> Works. >>>> >>>> On 24 February 2017 at 23:18, nop head <nop.head@gmail.com> wrote: >>>> >>>>> When i == len(values) you return values[i] but lists are indexed from >>>>> 0, so you are try to access one past the end, hence the undef. >>>>> >>>>> >>>>> >>>>> On 24 February 2017 at 23:10, Ari Diacou <ari.diacou@gmail.com> wrote: >>>>> >>>>>> >>>>>> >>>>>> I am trying to write arithmetic, geometric and harmonic mean >>>>>> functions in openscad. >>>>>> >>>>>> It appears I need to use recursion ( >>>>>> >>>>>> Here is my program: >>>>>> >>>>>> echo(sum([1,2,3])); >>>>>> function sum(values,i=0)=( >>>>>> (i==len(values)) ? >>>>>> values[i] : >>>>>> values[i] + sum(values, //f, >>>>>> i+1) >>>>>> ); >>>>>> >>>>>> The output should be 6. with the comment in line 5, the output is >>>>>> undef, if you uncomment the "f," you get 5 errors, not 3, which means there >>>>>> are too many calls. >>>>>> >>>>>> Can anyone give me some help? >>>>>> >>>>>> I took a look at the WikiBook, but it didnt help me much: >>>>>> https://en.wikibooks.org/w/index.php?title=OpenSCAD_User_Man >>>>>> ual/User-Defined_Functions_and_Modules&stable=0#Recursive_functions >>>>>> >>>>>> Or if you have already written the functions I want (product, sum, >>>>>> aritmentic mean, harmonic mean, and geometric mean) of a list of values, >>>>>> send me those. >>>>>> >>>>>> Thanks, >>>>>> Ari M Diacou, Metis Industries >>>>>> >>>>>> >>>>>> _______________________________________________ >>>>>> OpenSCAD mailing list >>>>>> Discuss@lists.openscad.org >>>>>> http://lists.openscad.org/mailman/listinfo/discuss_lists.openscad.org >>>>>> >>>>>> >>>>> >>>> >>>> _______________________________________________ >>>> OpenSCAD mailing list >>>> Discuss@lists.openscad.org >>>> http://lists.openscad.org/mailman/listinfo/discuss_lists.openscad.org >>>> >>>> >>> >>> _______________________________________________ >>> OpenSCAD mailing list >>> Discuss@lists.openscad.org >>> http://lists.openscad.org/mailman/listinfo/discuss_lists.openscad.org >>> >>> >> >> _______________________________________________ >> OpenSCAD mailing list >> Discuss@lists.openscad.org >> http://lists.openscad.org/mailman/listinfo/discuss_lists.openscad.org >> >> > > _______________________________________________ > OpenSCAD mailing list > Discuss@lists.openscad.org > http://lists.openscad.org/mailman/listinfo/discuss_lists.openscad.org > >

There is some code about similar functions in the Tips and Tricks <https://en.wikibooks.org/wiki/OpenSCAD_User_Manual/Tips_and_Tricks#Add_all_values_in_a_list> section of the Manual. The simpler and non-recursive solution I know for your case is: function sum(values) = [for(p=values) 1]*values; It works with list of numbers and list of vectors.

I think it works now: A=[2,3,4]; m=-2; echo(str("A=",A)); echo(str("power mean(A,",m,")=",power_mean(A,m))); echo(str("arithmetic mean=",mean(A))); echo(str("harmonic mean=",harmonic_mean(A))); echo(str("sum=",sum(A))); echo(str("product=",product(A))); echo(str("invert(A)=",invert(A))); echo(str("power_each(A,",m,")=",power_each(A,m))); function sum(values,i=0)=( //outputs the sum of a list of values //uses recursion, but takes advantage of OpenSCAD's automatic looping of certain recursive function formats. i==len(values) ? 0 : values[i] + sum(values, i+1) ); function product(values,i=0)=( //outputs the product of a list of values i==len(values) ? 1 : values[i]*product(values, i+1) ); function mean(values,i=0)=( //outputs the arithmetic mean of a list of values //uses recursion, but takes advantage of OpenSCAD's automatic looping of certain recursive function formats. //See https://en.wikipedia.org/wiki/Mean#Arithmetic_mean i==len(values) ? 0 : values[i] + sum(values, i+1) )/len(values); function geometric_mean(values)=pow(product(values),1/len(values)); //outputs the geometric mean of a list of values //uses recursion, but takes advantage of OpenSCAD's automatic looping of certain recursive function formats. See https://en.wikipedia.org/wiki/Mean#Geometric_mean function harmonic_mean(values,i=0)=len(values)/sum(invert(values)); //outputs the harmonic mean of a list of values //uses recursion, but takes advantage of OpenSCAD's automatic looping of certain recursive function formats. //See https://en.wikipedia.org/wiki/Mean#Harmonic_mean function invert(values)=[for(i=[0:len(values)-1]) 1/values[i]]; //inverts each value in a list function power_each(values,n)=[for(i=[0:len(values)-1]) pow(values[i],n)]; //returns a list of each value in a list raised to the power of n. n can be any value. function power_mean(values,m)=pow(sum(power_each(values,m))/len(values),1/m); //See https://en.wikipedia.org/wiki/Mean#Generalized_means On Fri, Feb 24, 2017 at 6:28 PM, Ari Diacou <ari.diacou@gmail.com> wrote: > That was the part of the wikibook i didn't understand, although I at least > updated the link to the wikipedia article. > > On Fri, Feb 24, 2017 at 6:25 PM, nop head <nop.head@gmail.com> wrote: > >> echo(sum([1,2,3])); >> >> function sum(values, i = 0, sum = 0) = >> i == len(values) ? sum : sum(values, i + 1, sum + values[i]); >> >> Is a better way to do it because it uses tail recursion. I.e. it ends by >> calling itself. That is optimised to a loop by OpenSCAD, so it doesn't run >> out of stack. >> >> On 24 February 2017 at 23:23, Ari Diacou <ari.diacou@gmail.com> wrote: >> >>> Nice, I like that format better. >>> >>> On Fri, Feb 24, 2017 at 6:21 PM, nop head <nop.head@gmail.com> wrote: >>> >>>> echo(sum([1,2,3])); >>>> function sum(values, i = 0) = >>>> i == len(values) ? 0 : values[i] + sum(values, i + 1); >>>> >>>> Works. >>>> >>>> On 24 February 2017 at 23:18, nop head <nop.head@gmail.com> wrote: >>>> >>>>> When i == len(values) you return values[i] but lists are indexed from >>>>> 0, so you are try to access one past the end, hence the undef. >>>>> >>>>> >>>>> >>>>> On 24 February 2017 at 23:10, Ari Diacou <ari.diacou@gmail.com> wrote: >>>>> >>>>>> >>>>>> >>>>>> I am trying to write arithmetic, geometric and harmonic mean >>>>>> functions in openscad. >>>>>> >>>>>> It appears I need to use recursion ( >>>>>> >>>>>> Here is my program: >>>>>> >>>>>> echo(sum([1,2,3])); >>>>>> function sum(values,i=0)=( >>>>>> (i==len(values)) ? >>>>>> values[i] : >>>>>> values[i] + sum(values, //f, >>>>>> i+1) >>>>>> ); >>>>>> >>>>>> The output should be 6. with the comment in line 5, the output is >>>>>> undef, if you uncomment the "f," you get 5 errors, not 3, which means there >>>>>> are too many calls. >>>>>> >>>>>> Can anyone give me some help? >>>>>> >>>>>> I took a look at the WikiBook, but it didnt help me much: >>>>>> https://en.wikibooks.org/w/index.php?title=OpenSCAD_User_Man >>>>>> ual/User-Defined_Functions_and_Modules&stable=0#Recursive_functions >>>>>> >>>>>> Or if you have already written the functions I want (product, sum, >>>>>> aritmentic mean, harmonic mean, and geometric mean) of a list of values, >>>>>> send me those. >>>>>> >>>>>> Thanks, >>>>>> Ari M Diacou, Metis Industries >>>>>> >>>>>> >>>>>> _______________________________________________ >>>>>> OpenSCAD mailing list >>>>>> Discuss@lists.openscad.org >>>>>> http://lists.openscad.org/mailman/listinfo/discuss_lists.openscad.org >>>>>> >>>>>> >>>>> >>>> >>>> _______________________________________________ >>>> OpenSCAD mailing list >>>> Discuss@lists.openscad.org >>>> http://lists.openscad.org/mailman/listinfo/discuss_lists.openscad.org >>>> >>>> >>> >>> _______________________________________________ >>> OpenSCAD mailing list >>> Discuss@lists.openscad.org >>> http://lists.openscad.org/mailman/listinfo/discuss_lists.openscad.org >>> >>> >> >> _______________________________________________ >> OpenSCAD mailing list >> Discuss@lists.openscad.org >> http://lists.openscad.org/mailman/listinfo/discuss_lists.openscad.org >> >> >