I have used an equation within the field calculator, that has previously worked in an older version of QGIS, I am currently using QGIS 3.6.2 the equation being:
(atan((xat(-1)-xat(0))/(yat(-1)-yat(0)))) * 180/3.14159 + (180 *(((yat(-1)-yat(0)) < 0) + (((xat(-1)-xat(0)) < 0 AND (yat(-1) - yat(0)) >0)*2)))
This is the answer found on a previous question within this forum that helped me to achieve the angle of each line within a layer. However I keep getting the error evaluation message using the newer version of QGIS saying...
An error occurred while evaluating the calculation string: Cannot convert 'inf' to double.
What does this mean?