diff --git a/NEWS b/NEWS
index 05fc96a5413b1a350bbe6ed5fef8329e80121729..651ad33db870f59f094ead417abdc060ec975bd7 100755
--- a/NEWS
+++ b/NEWS
@@ -12,7 +12,9 @@ NEWS/ChangeLog for hydroPSO
                           -) default value for the time-varying c2 was changed from (non-linearly increasing) 'TVc1.rng= c(1.8, 2.2)' to 
                              'TVc2.rng= c(1.05, 1.28)'. However, by default 'use.TVc2= FALSE' still.
                           -) default value for the time-varying lambda was changed from (non-linearly decreasing) 'TVlambda.rng= c(0.9, 0.1)' to 
-                             'TVlambda.rng= c(1, 0.25)'. However, by default 'use.TVlambda= FALSE'
+                             'TVlambda.rng= c(1, 0.25)'. However, by default 'use.TVlambda= FALSE' still.
+                          -) default value for the exponent of the time-varying lambda was changed from 'TVlambda.exp= 1.7' to 'TVlambda.exp= 1'.
+                             However, by default 'use.TVlambda= FALSE' still.
                           -) source code was tidy up
                              
 0.1-56	14-Jun-2012
diff --git a/R/PSO_v2012.R b/R/PSO_v2012.R
index 48b575c901980c756b384fcbfd00fdbde9933ace..b4b42594813f763f43ecd8852e225c266811fe24 100755
--- a/R/PSO_v2012.R
+++ b/R/PSO_v2012.R
@@ -1394,7 +1394,7 @@ hydroPSO <- function(
 	    use.IW = TRUE, IW.type=c("linear", "non-linear", "runif", "aiwf", "GLratio"), IW.w=1/(2*log(2)), IW.exp= 1, 
 	    use.TVc1= FALSE, TVc1.type=c("non-linear", "linear", "GLratio"), TVc1.rng= c(1.28, 1.05), TVc1.exp= 1.5, 
 	    use.TVc2= FALSE, TVc2.type=c("non-linear", "linear"), TVc2.rng= c(1.05, 1.28), TVc2.exp= 1.5, 
-	    use.TVlambda=FALSE, TVlambda.type=c("non-linear", "linear"), TVlambda.rng= c(1, 0.25), TVlambda.exp= 1.7, 
+	    use.TVlambda=FALSE, TVlambda.type=c("non-linear", "linear"), TVlambda.rng= c(1, 0.25), TVlambda.exp= 1, 
 	    use.RG = FALSE, RG.thr= 1.1e-4, RG.r= 0.8, RG.miniter= 5, # RG.r not used in reagrouping
 	    
 	    plot=FALSE,                
diff --git a/man/hydroPSO.Rd b/man/hydroPSO.Rd
index a739a1e416faf56ddb4ea03a04d8b36ad1352892..6d5e1b30000f1e1661cc05207178198a04bc5352 100755
--- a/man/hydroPSO.Rd
+++ b/man/hydroPSO.Rd
@@ -249,7 +249,7 @@ numeric, initial and final values for the percentage to limit the maximum veloci
   \item{TVlambda.exp}{
 OPTIONAL. only required when \code{use.TVlambda= TRUE} AND \code{TVlambda.type='non-linear'} \cr
 numeric, non-linear modulation index \cr
-When \code{TVlambda.type= linear} \code{TVlambda.exp} is automatically set to 1 
+When \code{TVlambda.type='linear'} \code{TVlambda.exp} is automatically set to 1 
 }
   \item{use.RG}{
 logical, indicates if the swarm should be regrouped when premature convergence is detected. When \code{use.RG=TRUE} the swarm is regrouped in a search space centred around the current global best. This updated search space is hoped to be both small enough for efficient search and large enough to allow the swarm to escape from stagnation (see Evers and Ghalia, 2009)