Forgot your password?
New user?
Decimal Division
Decimal Math in MPI
To fudge basic decimal operations in MPI, simply multiply all the relevant values by 10x10^n, where n is the desired level of precision, and then put the decimal point n+n characters from the end of the returned number. If you're dividing, only multiply the larger value by 10x10^n, and place the decimal point n characters from the end
Example: I want the answer to 10 / 3 to three decimal places:
@mpi {div:{mult:10,1000},3} --> 3333
Obviously 10 / 3 is not 3333, so we need to change this output to something that appears correct. To do this, we use some string manipulation techniques:
@mpi {with:n,{div:{mult:10,1000},3}, {if:{gt:{strlen:{&n}},3},\
{midstr:{&n},1,-4},0}.{midstr:{&n},-3,-1}} --> 3.333
So let's take those concepts and make them reusable:
@set me=_msgmacs/fdiv:{with:n,{div:{mult:{:1},1{left:,{:3},0}},{:2}},
{if:{gt:{strlen:{&n}},{:3}},{midstr:{&n},1,-{add:{:3},1}},0.{midstr:{&n},-{:3},-1}}}
Use {fdiv} like this: {fdiv:first number, second number, precision}.
In the code, I used {left} to add the appropriate number of zeroes to the 1. I may have forgotten if there is a more appropriate way of repeating way of repeating a string an arbitrary number of times, if one exists.
Since {midstr} has the annoying habit of being crappy, you must check to make sure that you don't grab -3 (third from last character) when you want a non-existent -4: hence the {if:{gt:{strlen... bit.
I hope someone else will carry this idea to completion, since this macro is mostly useless in isolation. A set of macros, capable of adding, multiplication, and so on, is more useful.
