H=syslin('c',352*poly(-5,'s')/poly([0,0,2000,200,25,1],'s','c')); clf();evans(H,100); sgrid()
In the above code the zero is at -5, the poles are at -20, -2.5+ 9.68i, -2.5- 9.68i , 0, and 0. Note the 2 imaginary poles. Which means that I should see 1 zero and 5 poles in the evens plot. When I run the code I see 1 zero and 3 poles all on the real, not imaginary) axis. So something is screwed up here! When I run the code I do see an instant flicker of the real evens code, and then this screwed up display with no sgrid at all. All the other code that I have cut and pasted into Scilab (Routh table, Nyquist and Bode plots) all work with no problems. I did check the roots of poly(-5,'s') and poly([0,0,2000,200,25,1],'s','c') and they do show the above mentioned zeros and poles, so it seems that the display is very screwed up. When I run the code in the cloud I get a very nice root locus plot with the 2 complex poles and with the sgrid also plotted! If anyone can think of why Scilab will not run this code correctly, I will be very grateful.
"When I run the code I see 1 zero and 3 poles all on the real, not imaginary) axis": This is not true when i execute your code on scilab. I do see a correct plot.