fix a small case to compare

dox/specification/brep_format/brep_format.md

@@ -1357,7 +1357,7 @@ N_{i,j}(u)=\frac{(u-\bar{u}_{i}) \cdot N_{i,j-1}(u) }{\bar{u}_{i+j-1}-\bar{u}_{i
 
 where  
 
-$$ \bar{u}_{i}=u_{j}\; (1\leq j\leq k,\; \sum_{l=1}^{j-1}q_{l}+1 \leq i \leq \sum_{l=1}^{j}q_{l}) . $$ 
+$$\bar{u}_{i}=u_{j}\; (1\leq j\leq k,\; \sum_{l=1}^{j-1}q_{l}+1 \leq i \leq \sum_{l=1}^{j}q_{l})$$
 
 The example record is interpreted as a B-spline curve with a rational flag *r*=1, a degree *m*=1, a pole count *n*=3, a multiplicity knot count *k*=5, weight poles *B<sub>1</sub>*=(0,1), *h<sub>1</sub>*=4, *B<sub>2</sub>*=(1,-2), *h<sub>2</sub>*=5 and *B<sub>3</sub>*=(2,3), *h<sub>3</sub>*=6 and multiplicity knots *u<sub>1</sub>*=0, *q<sub>1</sub>*=1, *u<sub>2</sub>*=0.25, *q<sub>2</sub>*=1, *u<sub>3</sub>*=0.5, *q<sub>3</sub>*=1, *u<sub>4</sub>*=0.75, *q<sub>4</sub>*=1 and *u<sub>5</sub>*=1, *q<sub>5</sub>*=1. The B-spline curve is defined  by the following parametric equation: