Calculate complex expression
Added by Ilias Moysidis about 1 year ago
What is the cleanest way of calculating the expression:
h = 5/9 * (e-10), where
e = 6.112 * 10 ^ (7.5 * tas / (237.7+tas)) * hurs / 100.
I only want to keep the h variable.
Replies (3)
RE: Calculate complex expression - Added by Karin Meier-Fleischer about 1 year ago
Hi Ilias,
you can use the expr operator, see https://code.mpimet.mpg.de/projects/cdo/embedded/cdo.pdf#subsection.2.7.1
cdo -expr,'h = ((5/9) * ((6.112 * 10 ^ (7.5 * tas / (237.7+tas)) * hurs / 100.)-10))' infile outfile
RE: Calculate complex expression - Added by Ilias Moysidis about 1 year ago
Thank you very much.
When I run the line of code that you gave me:
cdo -expr,'h = ((5/9) * ((6.112 * 10 ^ (7.5 * tas / (237.7+tas)) * hurs / 100)-10))' temp.nc temp2.nc
from the command line, it runs smoothly.
However, when I ran the code from the python wrapper:
Cdo().expr('h = ((5/9) * ((6.112 * 10 ^ (7.5 * tas / (237.7+tas)) * hurs / 100)-10))', input='temp.nc', output='temp2.nc')
I am getting the following error:
Error in calling operator expr with:
/usr/bin/cdo -O -s -expr,h = ((5/9) * ((6.112 * 10 ^ (7.5 * tas / (237.7+tas)) * hurs / 100)-10)) temp.nc temp2.nc<<<
STDOUT:
STDERR:/bin/sh: 1: Syntax error: "(" unexpected
Do you know why?
RE: Calculate complex expression - Added by Karin Meier-Fleischer about 1 year ago
Try
Cdo().expr("'h = ((5/9) * ((6.112 * 10 ^ (7.5 * tas / (237.7+tas)) * hurs / 100)-10))'", input='temp.nc', output='temp2.nc')