steveo
12-18-2022, 06:34 AM
low level question to help me with a development project.
for table lookups, the old ecms i'm used to dealing with usually use linear interpolation between cells. so in an imaginary table with 4 columns like 10,20,30,40 and a set of values like 2,3,4,5, a lookup of 10 would give you 2, but a lookup of 35 would give you 4.5.
so functionally if you have a pair of columns x0,x1 and a pair of values y0,y1 you could do something like y0+((x-x0)/(x1-x0))*(y1-y0) to find the value of the column position x
and in a table with both columns and rows, it's just bilinear, so you'd do a lookup against row and column and average it.
my question is do modern ECMs do any more smooth lookups such as cubic/bicubic splines for anything? i have used bicubic spline functions for 3d lookup where my table is low resolution and i know the output should be smooth, so i am wondering if this was used on any of the ECMs we work with.
for table lookups, the old ecms i'm used to dealing with usually use linear interpolation between cells. so in an imaginary table with 4 columns like 10,20,30,40 and a set of values like 2,3,4,5, a lookup of 10 would give you 2, but a lookup of 35 would give you 4.5.
so functionally if you have a pair of columns x0,x1 and a pair of values y0,y1 you could do something like y0+((x-x0)/(x1-x0))*(y1-y0) to find the value of the column position x
and in a table with both columns and rows, it's just bilinear, so you'd do a lookup against row and column and average it.
my question is do modern ECMs do any more smooth lookups such as cubic/bicubic splines for anything? i have used bicubic spline functions for 3d lookup where my table is low resolution and i know the output should be smooth, so i am wondering if this was used on any of the ECMs we work with.