u_error: discretization error
using PyPlot
rc("font", family="Arial", size=16.0)
fig = figure("FTCS", figsize=(14,6));
ax1 = fig[:add_subplot](1,2,1);
ax2 = fig[:add_subplot](1,2,2);
ax1.plot(x, u_e, lw=4, ls = "-", color="b", label="Exact solution")
ax1.plot(x, u_n, lw=4, ls = "--", color="r", label="FTCS solution")
ax1.set_xlabel("\$x\$")
ax1.set_ylabel("\$v\$")
ax1.set_title("Solution field")
ax1.set_xlim(-1,1)
ax1.legend(fontsize=14, loc=0)
ax2.plot(x, u_error, marker = "o", markeredgecolor="k",
markersize=8, color="g", lw=4)
ax2.set_xlabel("\$x\$")
ax2.set_ylabel("\$\epsilon\$")
ax2.set_title("Discretization error")
ax2.set_xlim(-1,1)
#ax2.legend(fontsize=14, loc=0)
plt[:subplot](ax1);
plt[:subplot](ax2);
fig.tight_layout()
fig.savefig("ftcs.pdf")
```
✝ ✆

**Listing A2.** Plotting script for contour plot. ✞ ☎

```