4.2 Ngspice

Ngspice is very reluctant to print calculated data to standard output, which makes it challenging for Guile Blocks to extract the result. One option is to use Ngspice’s print command, but this is designed for human readability, adding both headers and an index column. This hurts Ngspice’s abiility to run in a pipeline with an external graphing program, such as Gnuplot.

There are two options to resolve this. One is to use the ngspice-file language procedure and direct Ngspice to write the data to a csv file.

(make-block*
 #:language (ngspice-file <filename>)
 #:code "
.control
* ...
wrdata <filename> <data>
.endc
.end")

This will both write the calculated data and set the result field to <filename>.

Another solution is to make use of the ‘/dev/stdout’ special file.

(make-block*
 #:language ngspice-stdout
 #:code ".control
 * ...
 wrdata /dev/stdout <data>
 .endc
 .end")

Using this method, <data> will be written to standard output and set as the result field.