Correct numerical precision problems in doc test
Correct numerical precision problems in doc test

rafaelmds/fatiando,victortxa/fatiando,rafaelmds/fatiando,eusoubrasileiro/fatiando_seismic,victortxa/fatiando,eusoubrasileiro/fatiando,santis19/fatiando,mtb-za/fatiando,cmeessen/fatiando,drandykass/fatiando,eusoubrasileiro/fatiando,drandykass/fatiando,fatiando/fatiando,eusoubrasileiro/fatiando_seismic,mtb-za/fatiando,cmeessen/fatiando,eusoubrasileiro/fatiando,fatiando/fatiando,santis19/fatiando