Break out of potentially infinite rescaling loop after 20 iterations

Author: martin-frbg

SRC/zlartg.f

@@ -155,13 +155,13 @@ SUBROUTINE ZLARTG( F, G, CS, SN, R )
       FS = F
       GS = G
       COUNT = 0
-      IF( SCALE.GE.SAFMX2 .AND. COUNT .LT. 20) THEN
+      IF( SCALE.GE.SAFMX2 ) THEN
    10    CONTINUE
          COUNT = COUNT + 1
          FS = FS*SAFMN2
          GS = GS*SAFMN2
          SCALE = SCALE*SAFMN2
-         IF( SCALE.GE.SAFMX2 )
+         IF( SCALE.GE.SAFMX2 .AND. COUNT .LT. 20 )
      $      GO TO 10
       ELSE IF( SCALE.LE.SAFMN2 ) THEN
          IF( G.EQ.CZERO.OR.DISNAN( ABS( G ) ) ) THEN