diff options
Diffstat (limited to 'sys/vops/abav.gx')
| -rw-r--r-- | sys/vops/abav.gx | 46 |
1 files changed, 46 insertions, 0 deletions
diff --git a/sys/vops/abav.gx b/sys/vops/abav.gx new file mode 100644 index 00000000..0f519216 --- /dev/null +++ b/sys/vops/abav.gx @@ -0,0 +1,46 @@ +# Copyright(c) 1986 Association of Universities for Research in Astronomy Inc. + +# ABAV -- Vector block average. Each pixel in the output vector is the +# average of the input vector over a block of pixels. The input vector must +# be at least (nblocks * npix_per_block) pixels in length. + +procedure abav$t (a, b, nblocks, npix_per_block) + +PIXEL a[ARB] # input vector +PIXEL b[nblocks] # output vector +int nblocks # number of blocks (pixels in output vector) +int npix_per_block # number of input pixels per block + +$if (datatype == cs) +long sum, width +$else $if (datatype == il) +real sum, width +$else +PIXEL sum, width +$endif $endif + +int i, j +int block_offset, next_block, block_length + +begin + block_offset = 1 + block_length = npix_per_block + $if (datatype != x) + width = block_length + $else + width = complex (block_length, block_length) + $endif + + if (block_length <= 1) + call amov$t (a[block_offset], b, nblocks) + else { + do j = 1, nblocks { + next_block = block_offset + block_length + sum = 0 + do i = block_offset, next_block - 1 + sum = sum + a[i] + b[j] = sum / width + block_offset = next_block + } + } +end |