Multiplication of lists [Thyme]

[KarateBrot]

I don't know if it's on purpose or not but lists multiplicate like this in the console:
[a, b, c, d]*[w, x, y, z] = [a*w, b*x, c*y, d*z]

But let's say [a,b,c,d] and [w,x,y,z] are vectors.
So the scalar product should be [a,b,c,d]*[w,x,y,z] = a*w + b*x + c*y + d*z.
But in Thyme the result is (like I already said): [a*w, b*x, c*y, d*z]

- - - -

Just wanted you to know. And to kill two birds with one stone I will add a suggestion:

Just in case it's too complicated to implement it for lists in general I suggest to implement a new math function i.e. "math.scalar" which can calculate the scalar product of two vectors with the same dimensions.

To make it one could use the "bug" from above to add the components of i.e. [a*w, b*x, ...] together.

Code: Select all

math.scalar := (v1, v2) =>{
    temp := 0;
    v := v1 * v2;
    for(string.length(v), (i)=>{temp = temp + v(i)})
}


[emilk]

When one say "vector multiplication" one normally refer to one of: inner/scalar/dot product, outer product, and component wise product (or cross product, if the vectors are of length 3). I choose the component wise, because:

A) thyme is not a linear algebra library
B) lists aren't vectors
C) inner and outer products requires vectors to be either columns or rows (one of each), and Thyme has no way to dfferentiate between the two.
D) by choosing the component wise interpretation, we get the same behavior as for +,-,/ etc.

As you point out, one can easily implement this in Thyme anyway, but I'll make it a bit easier by adding the following function to thyme.cfg:

math.sum := (v)=>{
ret = 0;
for(string.length(v), (i)=>{
ret = ret + v(i)
});
ret
};


One can now implement the dot product as

inner = (a,b)=>{math.sum(a*b)};

[Kilinich]

how about adding list(i) = x function?
if it's hard to implement maybe just add infix?

for example:

string.setValue := (list, item, value) => {r := []; for(string.length(list), (i) => {i == item ? {r = r ++ [value]} : {r = r ++ [list(i)]}})};

infix 3 left: _@_ #= _ => string.setValue

in result we will have
a := [1,1,1,1]
a@3 #= 0