good progress, diff in nonlinear_op

testing/configs/Chang2011Fig2.toml

@@ -0,0 +1,19 @@
+name = "/Users/benoitsierro/tests/test_sc/Chang2011Fig2"
+
+wavelength = 800e-9
+shape = "gaussian"
+energy = 2.5e-6
+width = 30e-15
+
+core_radius = 10e-6
+model = "marcatili"
+gas_name = "argon"
+pressure = 1e5
+
+length = 0.1
+interpolation_range = [100e-9, 3000e-9]
+full_field = true
+dt = 0.1e-15
+t_num = 32768
+z_num = 128
+step_size = 2e-6