Control Systems: HP prime app, now with frequency, time domain and root locus plots

[StephenG1CMZ]

I haven't looked at the code, but when I have seen an inexplicable syntax error in my own code I have sometimes found it helpful to delete and retype a few lines near the syntax error.
I suspected a problematic non-breaking space or breaking space or tab etc. - but I haven't seen that for quite a while, so that might not help.