segredomap: separate manual ispace index calculation to own function
segredomap: separate manual ispace index calculation to own function

ihc/futhark,HIPERFIT/futhark,diku-dk/futhark,diku-dk/futhark,ihc/futhark,diku-dk/futhark,HIPERFIT/futhark,diku-dk/futhark,ihc/futhark,diku-dk/futhark,HIPERFIT/futhark