def _derX(self, x, y):
    '\n        Returns the first derivative of the function with respect to X at each\n        value in (x,y).  Only called internally by HARKinterpolator2D._derX.\n        '
    m = len(x)
    temp = np.zeros((m, self.funcCount))
    for j in range(self.funcCount):
        temp[:, j] = self.functions[j](x, y)
    temp[np.isnan(temp)] = np.inf
    i = np.argmin(temp, axis=1)
    dfdx = np.zeros_like(x)
    for j in range(self.funcCount):
        c = (i == j)
        dfdx[c] = self.functions[j].derivativeX(x[c], y[c])
    return dfdx
Returns the first derivative of the function with respect to X at each
value in (x,y).  Only called internally by HARKinterpolator2D._derX.
def _derX(self, x, y):
    '\n        Returns the first derivative of the function with respect to X at each\n        value in (x,y).  Only called internally by HARKinterpolator2D._derX.\n        '
    m = len(x)
    temp = np.zeros((m, self.funcCount))
    for j in range(self.funcCount):
        temp[:, j] = self.functions[j](x, y)
    temp[np.isnan(temp)] = np.inf
    i = np.argmin(temp, axis=1)
    dfdx = np.zeros_like(x)
    for j in range(self.funcCount):
        c = (i == j)
        dfdx[c] = self.functions[j].derivativeX(x[c], y[c])
    return dfdx