This allows for testing the results of the calculation. Typically, data_item_name is -node_dof but also other data items can be tested. The record with index data_item_index will be tested. If data_item_name is -node_dof then number can be -velx, -temp, etc. (see dof_label); else, by example, number is 3 states that the fourth value needs to be checked. The result should not differ more from value than tolerance.
For a calculation with no problems, the tn.log file contains a line stating that the calculation did start followed by a line stating that the calculation did end. If this is not precisely the case, some problem did occur or the targeted results differ too much. In the example below it is checked that the pressure in node 6 does not differ more than .
target_item 0 -node_dof 6 -pres
target_value 0 1.2 1.e-5
The chacked value, 1.2 in this case, has been found from a previous computation that is regarded as reliable. The present computed value is compared with the earlier one. If they agree within the specified tolerance, 1.e-5 in this case, then Tochnog is silent. If they do not, then Tochnog writes an error message into the file "tn.log".