This seems to be wrong.
val1=-7.14769e-05
convert xc: -format "%[fx:$val1]" info:
-24.4294
possible bug -fx with scientific notation IM 6.8.9.1 Q16
Re: possible bug -fx with scientific notation IM 6.8.9.1 Q16
We can reproduce the problem you posted and have a patch in ImageMagick 6.8.9-2 Beta, available by sometime tomorrow. Thanks.