zigabostner

Ideally, I would like to be able to use the following operations: (from https://www.libvips.org/API/current/libvips-arithmetic.html) ``` vips_add vips_subtract vips_multiply vips_divide vips_sign vips_sin vips_cos vips_atan2 vips_pow vips_relational vips_relational_const ```