Make sure js outputs a floating point number? It seems to mix floats and int!

Jun 9, 2011 at 11:57pm

Make sure js outputs a floating point number? It seems to mix floats and int!

I know this is really obscure, but I hope there’s a solution….

With this function:

function test(v){
     var msg = Effect[1];
    var num=v/127;

I seem to get a mix of int and floats coming from outlet.
If I feed it “test 1″ the ouput in max is:
Effect[1] 0.007874
If I feed it “test 0″ the ouput in max is:
Effect[1] 0

which, on the surface, seems like no problem. However, the fact that the “0″ is an integer type, rather than a float like “0.0″ is causing me sadness. For some reason, this change between floats and ints keeps the pattrstorage from reporting the “Effect[1] 0″ with all the other stream of messages that have floats. This bizarre wrinkle is causing me some grief, and I’m wondering if there’s a way to force that 0 into a 0.0 from within the js? I already tried parseFloat, which, as you might expect, didn’t work. I’m guessing this has to do with the bridge between js and max, and the fact that js only has the type “number” and doesn’t distinguish between float and int.
Anyway, I hope there’s a good solution. Thanks for listening!

Jun 10, 2011 at 8:50am

You can output a float by specifying the message type, for example:


This will make integers appear with a decimal point. That comes unstuck a bit if you want to have a message preceeding your number though.

Jun 10, 2011 at 2:11pm

A nice tip to be treasured for the future, but, that msg is pretty important! I suppose I could do 2 outlets, then pack them in Max, but that would have other irritating consequences. Dammit!

Jun 11, 2011 at 3:41am

Yeah, I like that one too!

Pete: have you tried toFixed()? Or maybe, cast the 0 to a string?

Jun 12, 2011 at 9:55am

This will probably throw up some sort of problems but it might just be a way you can sneak past the javascript/max boundary the way you want. Clearly it is less than ideal!


Jun 12, 2011 at 3:03pm

@aumonra: toFixed! I had a thought about something like that. However, I tried it, and it ends up casting the number as a symbol:
“my msg” “0.0000″
And, given that this is all for controller data, which could be a heavy stream, I really don’t think it’s a good idea to get into symbol to number conversion on the entire stream.
@luke: also considered, but , yeah, I think that would end up causing more problems than solving.

I guess I will just have to abandon all hope of outputmode 2 on pattrstorage, whose “change” filter seems to be the real problem here, and try out outputmode 1….

Thanks for all the suggestions! It’s details like this that provide a salve of learning amid a sting of irritation.


Jun 21, 2011 at 3:07pm

Just an off-the-wall idea… you could hang a [t f] object after the [js] object to “typecast” any ints to floats. In your case you’d have to [unpack] your message and then [pack] it up again, but it might be a workaround.

‘zat help?

Jun 21, 2011 at 5:03pm

Sure, that would work, and I could also just use 2 outlets in the js and avoid an unpack. But its just clumsy. Ultimately, I changed my outputmode on the pattrstorage so it doesn’t have a change filter. This has been ok so far, but as I proceed with testing, it could end up outputting too much data. Keeping my fingers crossed!

Sep 13, 2011 at 10:26pm

For the sake of archive, here’s what I did. I changed the output mode on an as-need basis:

Apr 2, 2013 at 7:48pm

Sorry to revive this old thread, but I just came upon this same thing when trying to generate a list of filter coefs for cascade~ using a javascript. All coefs that were set as 0. (for unity filters) came out as ints (just 0) in the list and cascade~ complained that the list had to be all floats. I got around it by using Luke Hall’s solution, which is less than ideal- doing something like this in my script

coefs[i+0] = 0.99999999999999999999999999; //stupid hack to get float output in a list
coefs[i+1] = 0.00000000000000000000000001;
coefs[i+2] = 0.00000000000000000000000001;
coefs[i+3] = 0.00000000000000000000000001;
coefs[i+4] = 0.00000000000000000000000001;

and it worked. But there really should be a better way to do this. I’d like a way to specify what type of data an array is interpreted as when sent out of a js object as a list.

Sure – i could in this case type the output as “float”, output individual floats and then use a [zl group] to make them into a list… or maybe do something with a coll or dict… but that seems like significantly more extra work when you just want a list of floats. And you need to be very careful with [zl group] if your desired list length can change – been through that one more times than i want to count :)


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