Hello,

I'm trying to make a spatially resolved BPT. The problem is that i need to make an "if" parameter to define a specific region. Something like that:

mask=mask*0
for i=0, size(f[*,0,0],/n_elements)-1, 1 do begin
for j=0, size(f[0,*,0],/n_elements)-1, 1 do begin
if alog10(OIII[i,j]/Hb[i,j]) gt 0.0 then begin
mask[i,j]=1
endif
endfor
endfor

Those OIII and Hb are the y axis. The x axis is NII/Ha, so this parameter only includes one axis. This are emission lines that i have in data cube.
This mask does a line "cut" in my diagram but i need to make that line become an curve somehow. More precisely i need 4 regions between this curves:

x=findgen(135)*0.01-1.49
y= 0.61/(x-0.05)+1.3

x=findgen(175)*0.01-1.49
y= 0.61/(x-0.47)+1.19

x=findgen(94)*0.01-0.435
y= 1.01 * x + 0.48

I would appreciate any help to know how to declare those regions. Kinda lost right now.