Added interpolation matrix. Not sure its working since my canopy is playing tricks

SimPEG/interpmat.py

@@ -0,0 +1,86 @@
+from scipy import sparse as sp
+from sputils import sdiag
+from utils import sub2ind, ndgrid, mkvc
+import numpy as np
+
+def interpmat(x,y,z,xr,yr,zr):
+#
+# This function does local linear interpolation
+# computed for each receiver point in turn
+#
+# [Q] = linint(x,y,z,xr,yr,zr)
+# Interpolation matrix 
+#
+
+    nx = size(x)
+    ny = size(y)
+    nz = size(z)
+
+    np = size(xr)
+
+    #Q = spalloc(np,nx*ny*nz,8*np);
+    Q = sparse.coo_matrix((0.0,(0,0)),shape=(nx*ny*nz,8*np))
+    
+    for i in range(0, np): 
+        im = amin(abs(xr[i]-x))
+        if  xr[i] - x[im] >= 0:  # Point on the left 
+                 ind_x[0] = im;   ind_x[1] = im+1
+        else:                    # Point on the right
+                 ind_x[0] = im-1; ind_x[1] = im
+       
+       
+        dx[0] = xr[i] - x[ind_x[0]]
+        dx[1] = x[ind_x[1]] - xr[i]
+
+        im = amin(abs(yr[i] - y)) 
+        if  yr[i] - y[im] >= 0:     # Point on the left
+            ind_y[0] = im; ind_y[1] = im+1
+        else:                       # Point on the right
+            ind_y[0] = im-1; ind_y[1] = im
+            
+
+        dy[0] = yr[i] - y[ind_y[0]]
+        dy[1] = y[ind_y[1]] - yr[i];
+
+        im = amin(abs(zr[i] - z));
+        if  zr(i) -z(im) >= 0:  # Point on the left
+            ind_z[0] = im;  ind_z[1] = im+1
+        else:                    # Point on the right
+            ind_z[0] = im-1; ind_z[1] = im;
+
+        dz[0] = zr[i] - z[ind_z[0]]; dz[1] = z[ind_z[1]] - zr[i]      
+
+        Dx =  x[ind_x[1]] - x[ind_x[0]]
+        Dy =  y[ind_y[1]] - y[ind_y[0]]
+        Dz =  z[ind_z[1]] - z[ind_z[0]]  
+        dv = Dx*Dy*Dz
+
+      # Get the row in the matrix
+        v = zeros([nx, ny,nz]);
+
+        v[ ind_x[0],  ind_y[0],  ind_z[0]] = (1-dx[0]/Dx)*(1-dy[0]/Dy)*(1-dz[0]/Dz)
+        v[ ind_x[0],  ind_y[1],  ind_z[0]] = (1-dx[0]/Dx)*(1-dy[1]/Dy)*(1-dz[0]/Dz);
+        v[ ind_x[1],  ind_y[0],  ind_z[0]] = (1-dx[1]/Dx)*(1-dy[0]/Dy)*(1-dz[0]/Dz);
+        v[ ind_x[1],  ind_y[1],  ind_z[0]] = (1-dx[1]/Dx)*(1-dy[1]/Dy)*(1-dz[0]/Dz);
+        v[ ind_x[0],  ind_y[0],  ind_z[1]] = (1-dx[0]/Dx)*(1-dy[0]/Dy)*(1-dz[1]/Dz);
+        v[ ind_x[0],  ind_y[1],  ind_z[1]] = (1-dx[0]/Dx)*(1-dy[1]/Dy)*(1-dz[1]/Dz);
+        v[ ind_x[1],  ind_y[0],  ind_z[1]] = (1-dx[1]/Dx)*(1-dy[0]/Dy)*(1-dz[1]/Dz);
+        v[ ind_x[1],  ind_y[1],  ind_z[1]] = (1-dx[1]/Dx)*(1-dy[1]/Dy)*(1-dz[1]/Dz);
+
+     
+        Q[i,:] = v.flatten('F')
+        
+    return Q
+    
+    
+if __name__ == '__main__':
+    x = np.array([1, 2, 3, 4])
+    y = np.array([1, 2, 3, 4, 5])
+    z = np.array([0, 1, 4, 6])
+  
+    xr = np.array([2.5,3.2])
+    yr = np.array([2.4,3.6])
+    zr = np.array([2.5,3.9])
+      
+    A = interpmat(x,y,z,xr,yr,zr)
+