Fixing docs for pearl necklace model.

Fixes #952

sasmodels/models/pearl_necklace.py

@@ -24,14 +24,14 @@
 
 .. math::
 
-    S_{ss}(q) &= sm_s^2\psi^2(q)[\frac{N}{1-sin(qA)/qA}-\frac{N}{2}-
-        \frac{1-(sin(qA)/qA)^N}{(1-sin(qA)/qA)^2}\cdot\frac{sin(qA)}{qA}] \\
-    S_{ff}(q) &= sm_r^2[M\{2\Lambda(q)-(\frac{sin(ql/2)}{ql/2})\}+
+    S_{ss}(q) &= 2m_s^2\psi^2(q)\left[\frac{N}{1-sin(qA)/qA}-\frac{N}{2}-
+        \frac{1-(sin(qA)/qA)^N}{(1-sin(qA)/qA)^2}\cdot\frac{sin(qA)}{qA}\right] \\
+    S_{ff}(q) &= m_r^2\left[M\left\{2\Lambda(q)-\left(\frac{sin(ql/2)}{ql/2}\right)\right\}+
         \frac{2M\beta^2(q)}{1-sin(qA)/qA}-2\beta^2(q)\cdot
-        \frac{1-(sin(qA)/qA)^M}{(1-sin(qA)/qA)^2}] \\
-    S_{fs}(q) &= m_r \beta (q) \cdot m_s \psi (q) \cdot 4[
+        \frac{1-(sin(qA)/qA)^M}{(1-sin(qA)/qA)^2}\right] \\
+    S_{fs}(q) &= m_r \beta (q) \cdot m_s \psi (q) \cdot 4\left[
         \frac{N-1}{1-sin(qA)/qA}-\frac{1-(sin(qA)/qA)^{N-1}}{(1-sin(qA)/qA)^2}
-        \cdot \frac{sin(qA)}{qA}] \\
+        \cdot \frac{sin(qA)}{qA}\right] \\
     \psi(q) &= 3 \cdot \frac{sin(qR)-(qR)\cdot cos(qR)}{(qR)^3} \\
     \Lambda(q) &= \frac{\int_0^{ql}\frac{sin(t)}{t}dt}{ql} \\
     \beta(q) &= \frac{\int_{qR}^{q(A-R)}\frac{sin(t)}{t}dt}{ql}
@@ -64,9 +64,9 @@
 Authorship and Verification
 ----------------------------
 
-* **Author:** 
-* **Last Modified by:** 
-* **Last Reviewed by:** 
+* **Author:**
+* **Last Modified by:**
+* **Last Reviewed by:**
 * **Source added by :** Steve King **Date:** March 25, 2019
 """