#grilla

y11= -50
y0, y1 = -90, 90
dy=1.0
yvec = arange(y0,y11,dy)
ny = size(yvec)
Rt=6371
beta=math.pi/180
R=beta*Rt 
L=zeros(ny,float)#arc vector
L[0]=2*math.pi*R
for i in range(1, ny):
    L[i]=2*math.pi*R*(i+1)

nnx=zeros(ny,float)
nnx=L/L[0]
nnx=200/nnx
nnx=nnx.round()
div=np.array([1,2,3,4,5,6,8,9,10,12,15,16,18,20,24,25,30,36,
40,45,48,50,60,72,75,80,90,100,120,144,150,180,200,225,240,300,360,
400,450,600,720,900,1200,1800,3600])
vnx=zeros(ny,float)

for i in range(0, ny):
    a=nnx[i]
    for j in range(0, 45):
        b=div[j]
        if b<=a:
           vnx[i]=b

vnx[13:40]=12
li=(L/3600)*vnx