Dynamic Array arithmetic

NEO · Post by **NEO** » Thu Jul 12, 2007 8:05 am

Hi,
I am trying to do some arithmetic on an array. I have two sets of data.
X=[1,2,3]
Y=[10,20,30]

I would like to be able to do some arithmetic like this.

SUM(XY)-SUM(X)SUM(Y) = (10+40+90)-(1+2+3)*(10+20+30)

I know how to multiply arrays but not sure about summing elements in an array. I have a feeling its real simple but I havent thought through it

Any help highly appreciated as always.
Thanks.

NEO · Post by **NEO** » Thu Jul 12, 2007 8:33 am

Turns out it is very simple. SUM(X) gives the sum of all elements in the array !

NEO · Post by **NEO** » Thu Jul 12, 2007 8:34 am

Did anyone try to do Matrix algebra using dynamic arrays in Basic ?

NEO · Post by **NEO** » Thu Jul 12, 2007 12:09 pm

As part of the same topic, how do you multiply a vector with a scalar.

For example.

X=[1,2,3,4,5]
Y=2*X=[2,4,6,8,10]

kcbland · Post by **kcbland** » Thu Jul 12, 2007 1:06 pm

Look in your DS BASIC manual at the MULS function.

kcbland · Post by **kcbland** » Thu Jul 12, 2007 1:11 pm

Actually, look at the following:

ADDS
DIVS
MULS
SUBS

They do a lot of array mathematics. To simulate vector with a scalar, simply convert your single value into an array of that same value repeated as many times in your list.

ray.wurlod · Post by **ray.wurlod** » Thu Jul 12, 2007 2:03 pm

Code: Select all

vector * REUSE(scalar)

If you have multi-valued fields in your dynamic array SUM() will only total the values into fields. Prefer SUMMATION() in this case.