XSLT 1.0: set variable value depending on condition -

i want set value of variable(b). if variable(a) not empty variable(b) equals variable(a). if empty set value 0.00. have tried couple of methods none of works.

<xsl:variable name="achecker" select="current()/money[last()]/value"/> 

method 1:

<xsl:variable name="b">     <xsl:choose>         <xsl:when test="$achecker != ''">             <xsl:value-of select="$achecker"/>         <xsl:when>         <xsl:otherwise>             <xsl:value-of select="0.00"/>         </xsl:otherwise>     </xsl:choose> </xsl:variable> 

i tried changing

<xsl:when test="$achecker != ''"> 

to

<xsl:when test="not($achecker)"> 

method 2:

<xsl:choose>     <xsl:when test="$achecker != ''">         <xsl:variable name="b" select="$achecker"/>     <xsl:when>     <xsl:otherwise>         <xsl:variable name="b" select="0.00"/>     </xsl:otherwise> </xsl:choose>