diff --git a/calc.go b/calc.go
index 20d5b5e..57b2cda 100644
--- a/calc.go
+++ b/calc.go
@@ -374,6 +374,7 @@ type formulaFuncs struct {
 //    CONCATENATE
 //    CONFIDENCE
 //    CONFIDENCE.NORM
+//    CONFIDENCE.T
 //    CORREL
 //    COS
 //    COSH
@@ -588,6 +589,7 @@ type formulaFuncs struct {
 //    PERCENTRANK
 //    PERMUT
 //    PERMUTATIONA
+//    PHI
 //    PI
 //    PMT
 //    POISSON.DIST
@@ -6805,7 +6807,7 @@ func (fn *formulaFuncs) CONFIDENCE(argsList *list.List) formulaArg {
 // confidence value that can be used to construct the confidence interval for
 // a population mean, for a supplied probability and sample size. It is
 // assumed that the standard deviation of the population is known. The syntax
-// of the Confidence.Norm function is:
+// of the function is:
 //
 //    CONFIDENCE.NORM(alpha,standard_dev,size)
 //
@@ -6813,6 +6815,42 @@ func (fn *formulaFuncs) CONFIDENCEdotNORM(argsList *list.List) formulaArg {
 	return fn.confidence("CONFIDENCE.NORM", argsList)
 }
 
+// CONFIDENCEdotT function uses a Student's T-Distribution to calculate a
+// confidence value that can be used to construct the confidence interval for
+// a population mean, for a supplied probablity and supplied sample size. It
+// is assumed that the standard deviation of the population is known. The
+// syntax of the function is:
+//
+//    CONFIDENCE.T(alpha,standard_dev,size)
+//
+func (fn *formulaFuncs) CONFIDENCEdotT(argsList *list.List) formulaArg {
+	if argsList.Len() != 3 {
+		return newErrorFormulaArg(formulaErrorVALUE, "CONFIDENCE.T requires 3 arguments")
+	}
+	var alpha, standardDev, size formulaArg
+	if alpha = argsList.Front().Value.(formulaArg).ToNumber(); alpha.Type != ArgNumber {
+		return alpha
+	}
+	if standardDev = argsList.Front().Next().Value.(formulaArg).ToNumber(); standardDev.Type != ArgNumber {
+		return standardDev
+	}
+	if size = argsList.Back().Value.(formulaArg).ToNumber(); size.Type != ArgNumber {
+		return size
+	}
+	if alpha.Number <= 0 || alpha.Number >= 1 || standardDev.Number <= 0 || size.Number < 1 {
+		return newErrorFormulaArg(formulaErrorNUM, formulaErrorNUM)
+	}
+	if size.Number == 1 {
+		return newErrorFormulaArg(formulaErrorDIV, formulaErrorDIV)
+	}
+	return newNumberFormulaArg(standardDev.Number * calcIterateInverse(calcInverseIterator{
+		name: "CONFIDENCE.T",
+		fp:   alpha.Number,
+		fDF:  size.Number - 1,
+		nT:   2,
+	}, size.Number/2, size.Number) / math.Sqrt(size.Number))
+}
+
 // COVAR function calculates the covariance of two supplied sets of values. The
 // syntax of the function is:
 //
@@ -8891,6 +8929,22 @@ func (fn *formulaFuncs) PERMUTATIONA(argsList *list.List) formulaArg {
 	return newNumberFormulaArg(math.Pow(num, numChosen))
 }
 
+// PHI function returns the value of the density function for a standard normal
+// distribution for a supplied number. The syntax of the function is:
+//
+//    PHI(x)
+//
+func (fn *formulaFuncs) PHI(argsList *list.List) formulaArg {
+	if argsList.Len() != 1 {
+		return newErrorFormulaArg(formulaErrorVALUE, "PHI requires 1 argument")
+	}
+	x := argsList.Front().Value.(formulaArg).ToNumber()
+	if x.Type != ArgNumber {
+		return x
+	}
+	return newNumberFormulaArg(0.39894228040143268 * math.Exp(-(x.Number*x.Number)/2))
+}
+
 // QUARTILE function returns a requested quartile of a supplied range of
 // values. The syntax of the function is:
 //
@@ -13122,7 +13176,7 @@ func validateFrequency(freq float64) bool {
 	return freq == 1 || freq == 2 || freq == 4
 }
 
-// ACCRINT function returns the accrued interest for a security that pays
+// ACCRINT function returns the accrued interest in a security that pays
 // periodic interest. The syntax of the function is:
 //
 //    ACCRINT(issue,first_interest,settlement,rate,par,frequency,[basis],[calc_method])
@@ -13166,7 +13220,7 @@ func (fn *formulaFuncs) ACCRINT(argsList *list.List) formulaArg {
 	return newNumberFormulaArg(par.Number * rate.Number * frac1.Number)
 }
 
-// ACCRINTM function returns the accrued interest for a security that pays
+// ACCRINTM function returns the accrued interest in a security that pays
 // interest at maturity. The syntax of the function is:
 //
 //    ACCRINTM(issue,settlement,rate,[par],[basis])
diff --git a/calc_test.go b/calc_test.go
index 689fd92..c553d12 100644
--- a/calc_test.go
+++ b/calc_test.go
@@ -879,6 +879,8 @@ func TestCalcCellValue(t *testing.T) {
 		"=CONFIDENCE(0.05,0.07,100)": "0.0137197479028414",
 		// CONFIDENCE.NORM
 		"=CONFIDENCE.NORM(0.05,0.07,100)": "0.0137197479028414",
+		// CONFIDENCE.T
+		"=CONFIDENCE.T(0.05,0.07,100)": "0.0138895186611049",
 		// CORREL
 		"=CORREL(A1:A5,B1:B5)": "1",
 		// COUNT
@@ -1122,6 +1124,11 @@ func TestCalcCellValue(t *testing.T) {
 		// PERMUTATIONA
 		"=PERMUTATIONA(6,6)": "46656",
 		"=PERMUTATIONA(7,6)": "117649",
+		// PHI
+		"=PHI(-1.5)": "0.129517595665892",
+		"=PHI(0)":    "0.398942280401433",
+		"=PHI(0.1)":  "0.396952547477012",
+		"=PHI(1)":    "0.241970724519143",
 		// QUARTILE
 		"=QUARTILE(A1:A4,2)": "1.5",
 		// QUARTILE.EXC
@@ -2643,6 +2650,16 @@ func TestCalcCellValue(t *testing.T) {
 		"=CORREL()":            "CORREL requires 2 arguments",
 		"=CORREL(A1:A3,B1:B5)": "#N/A",
 		"=CORREL(A1:A1,B1:B1)": "#DIV/0!",
+		// CONFIDENCE.T
+		"=CONFIDENCE.T()":               "CONFIDENCE.T requires 3 arguments",
+		"=CONFIDENCE.T(\"\",0.07,100)":  "strconv.ParseFloat: parsing \"\": invalid syntax",
+		"=CONFIDENCE.T(0.05,\"\",100)":  "strconv.ParseFloat: parsing \"\": invalid syntax",
+		"=CONFIDENCE.T(0.05,0.07,\"\")": "strconv.ParseFloat: parsing \"\": invalid syntax",
+		"=CONFIDENCE.T(0,0.07,100)":     "#NUM!",
+		"=CONFIDENCE.T(1,0.07,100)":     "#NUM!",
+		"=CONFIDENCE.T(0.05,0,100)":     "#NUM!",
+		"=CONFIDENCE.T(0.05,0.07,0)":    "#NUM!",
+		"=CONFIDENCE.T(0.05,0.07,1)":    "#DIV/0!",
 		// COUNTBLANK
 		"=COUNTBLANK()":    "COUNTBLANK requires 1 argument",
 		"=COUNTBLANK(1,2)": "COUNTBLANK requires 1 argument",
@@ -2985,6 +3002,9 @@ func TestCalcCellValue(t *testing.T) {
 		"=PERMUTATIONA(0,\"\")": "strconv.ParseFloat: parsing \"\": invalid syntax",
 		"=PERMUTATIONA(-1,0)":   "#N/A",
 		"=PERMUTATIONA(0,-1)":   "#N/A",
+		// PHI
+		"=PHI()":     "PHI requires 1 argument",
+		"=PHI(\"\")": "strconv.ParseFloat: parsing \"\": invalid syntax",
 		// QUARTILE
 		"=QUARTILE()":           "QUARTILE requires 2 arguments",
 		"=QUARTILE(A1:A4,\"\")": "strconv.ParseFloat: parsing \"\": invalid syntax",
diff --git a/drawing.go b/drawing.go
index 1daa912..d0e9135 100644
--- a/drawing.go
+++ b/drawing.go
@@ -957,14 +957,14 @@ func (f *File) drawChartSeriesDLbls(formatSet *formatChart) *cDLbls {
 
 // drawPlotAreaCatAx provides a function to draw the c:catAx element.
 func (f *File) drawPlotAreaCatAx(formatSet *formatChart) []*cAxs {
-	min := &attrValFloat{Val: float64Ptr(formatSet.XAxis.Minimum)}
-	max := &attrValFloat{Val: float64Ptr(formatSet.XAxis.Maximum)}
-	if formatSet.XAxis.Minimum == 0 {
-		min = nil
-	}
-	if formatSet.XAxis.Maximum == 0 {
+	max := &attrValFloat{Val: formatSet.XAxis.Maximum}
+	min := &attrValFloat{Val: formatSet.XAxis.Minimum}
+	if formatSet.XAxis.Maximum == nil {
 		max = nil
 	}
+	if formatSet.XAxis.Minimum == nil {
+		min = nil
+	}
 	axs := []*cAxs{
 		{
 			AxID: &attrValInt{Val: intPtr(754001152)},
@@ -1006,14 +1006,14 @@ func (f *File) drawPlotAreaCatAx(formatSet *formatChart) []*cAxs {
 
 // drawPlotAreaValAx provides a function to draw the c:valAx element.
 func (f *File) drawPlotAreaValAx(formatSet *formatChart) []*cAxs {
-	min := &attrValFloat{Val: float64Ptr(formatSet.YAxis.Minimum)}
-	max := &attrValFloat{Val: float64Ptr(formatSet.YAxis.Maximum)}
-	if formatSet.YAxis.Minimum == 0 {
-		min = nil
-	}
-	if formatSet.YAxis.Maximum == 0 {
+	max := &attrValFloat{Val: formatSet.YAxis.Maximum}
+	min := &attrValFloat{Val: formatSet.YAxis.Minimum}
+	if formatSet.YAxis.Maximum == nil {
 		max = nil
 	}
+	if formatSet.YAxis.Minimum == nil {
+		min = nil
+	}
 	var logBase *attrValFloat
 	if formatSet.YAxis.LogBase >= 2 && formatSet.YAxis.LogBase <= 1000 {
 		logBase = &attrValFloat{Val: float64Ptr(formatSet.YAxis.LogBase)}
@@ -1060,14 +1060,14 @@ func (f *File) drawPlotAreaValAx(formatSet *formatChart) []*cAxs {
 
 // drawPlotAreaSerAx provides a function to draw the c:serAx element.
 func (f *File) drawPlotAreaSerAx(formatSet *formatChart) []*cAxs {
-	min := &attrValFloat{Val: float64Ptr(formatSet.YAxis.Minimum)}
-	max := &attrValFloat{Val: float64Ptr(formatSet.YAxis.Maximum)}
-	if formatSet.YAxis.Minimum == 0 {
-		min = nil
-	}
-	if formatSet.YAxis.Maximum == 0 {
+	max := &attrValFloat{Val: formatSet.YAxis.Maximum}
+	min := &attrValFloat{Val: formatSet.YAxis.Minimum}
+	if formatSet.YAxis.Maximum == nil {
 		max = nil
 	}
+	if formatSet.YAxis.Minimum == nil {
+		min = nil
+	}
 	return []*cAxs{
 		{
 			AxID: &attrValInt{Val: intPtr(832256642)},
diff --git a/go.mod b/go.mod
index 16874b2..116b7a1 100644
--- a/go.mod
+++ b/go.mod
@@ -6,10 +6,10 @@ require (
 	github.com/mohae/deepcopy v0.0.0-20170929034955-c48cc78d4826
 	github.com/richardlehane/mscfb v1.0.4
 	github.com/stretchr/testify v1.7.0
-	github.com/xuri/efp v0.0.0-20220216053911-6d8731f62184
-	github.com/xuri/nfp v0.0.0-20220215121256-71f1502108b5
-	golang.org/x/crypto v0.0.0-20220214200702-86341886e292
+	github.com/xuri/efp v0.0.0-20220407160117-ad0f7a785be8
+	github.com/xuri/nfp v0.0.0-20220409054826-5e722a1d9e22
+	golang.org/x/crypto v0.0.0-20220408190544-5352b0902921
 	golang.org/x/image v0.0.0-20211028202545-6944b10bf410
-	golang.org/x/net v0.0.0-20220127200216-cd36cc0744dd
+	golang.org/x/net v0.0.0-20220407224826-aac1ed45d8e3
 	golang.org/x/text v0.3.7
 )
diff --git a/go.sum b/go.sum
index a4051d4..8ca6233 100644
--- a/go.sum
+++ b/go.sum
@@ -11,17 +11,17 @@ github.com/richardlehane/msoleps v1.0.1/go.mod h1:BWev5JBpU9Ko2WAgmZEuiz4/u3ZYTK
 github.com/stretchr/objx v0.1.0/go.mod h1:HFkY916IF+rwdDfMAkV7OtwuqBVzrE8GR6GFx+wExME=
 github.com/stretchr/testify v1.7.0 h1:nwc3DEeHmmLAfoZucVR881uASk0Mfjw8xYJ99tb5CcY=
 github.com/stretchr/testify v1.7.0/go.mod h1:6Fq8oRcR53rry900zMqJjRRixrwX3KX962/h/Wwjteg=
-github.com/xuri/efp v0.0.0-20220216053911-6d8731f62184 h1:9nchVQT/GVLRvOnXzx+wUvSublH/jG/ANV4MxBnGhUA=
-github.com/xuri/efp v0.0.0-20220216053911-6d8731f62184/go.mod h1:ybY/Jr0T0GTCnYjKqmdwxyxn2BQf2RcQIIvex5QldPI=
-github.com/xuri/nfp v0.0.0-20220215121256-71f1502108b5 h1:Pg6lKJe2FUZTalbUygJxgW1ke2re9lY3YW5TKb+Pxe4=
-github.com/xuri/nfp v0.0.0-20220215121256-71f1502108b5/go.mod h1:WwHg+CVyzlv/TX9xqBFXEZAuxOPxn2k1GNHwG41IIUQ=
-golang.org/x/crypto v0.0.0-20220214200702-86341886e292 h1:f+lwQ+GtmgoY+A2YaQxlSOnDjXcQ7ZRLWOHbC6HtRqE=
-golang.org/x/crypto v0.0.0-20220214200702-86341886e292/go.mod h1:IxCIyHEi3zRg3s0A5j5BB6A9Jmi73HwBIUl50j+osU4=
+github.com/xuri/efp v0.0.0-20220407160117-ad0f7a785be8 h1:3X7aE0iLKJ5j+tz58BpvIZkXNV7Yq4jC93Z/rbN2Fxk=
+github.com/xuri/efp v0.0.0-20220407160117-ad0f7a785be8/go.mod h1:ybY/Jr0T0GTCnYjKqmdwxyxn2BQf2RcQIIvex5QldPI=
+github.com/xuri/nfp v0.0.0-20220409054826-5e722a1d9e22 h1:OAmKAfT06//esDdpi/DZ8Qsdt4+M5+ltca05dA5bG2M=
+github.com/xuri/nfp v0.0.0-20220409054826-5e722a1d9e22/go.mod h1:WwHg+CVyzlv/TX9xqBFXEZAuxOPxn2k1GNHwG41IIUQ=
+golang.org/x/crypto v0.0.0-20220408190544-5352b0902921 h1:iU7T1X1J6yxDr0rda54sWGkHgOp5XJrqm79gcNlC2VM=
+golang.org/x/crypto v0.0.0-20220408190544-5352b0902921/go.mod h1:IxCIyHEi3zRg3s0A5j5BB6A9Jmi73HwBIUl50j+osU4=
 golang.org/x/image v0.0.0-20211028202545-6944b10bf410 h1:hTftEOvwiOq2+O8k2D5/Q7COC7k5Qcrgc2TFURJYnvQ=
 golang.org/x/image v0.0.0-20211028202545-6944b10bf410/go.mod h1:023OzeP/+EPmXeapQh35lcL3II3LrY8Ic+EFFKVhULM=
 golang.org/x/net v0.0.0-20211112202133-69e39bad7dc2/go.mod h1:9nx3DQGgdP8bBQD5qxJ1jj9UTztislL4KSBs9R2vV5Y=
-golang.org/x/net v0.0.0-20220127200216-cd36cc0744dd h1:O7DYs+zxREGLKzKoMQrtrEacpb0ZVXA5rIwylE2Xchk=
-golang.org/x/net v0.0.0-20220127200216-cd36cc0744dd/go.mod h1:CfG3xpIq0wQ8r1q4Su4UZFWDARRcnwPjda9FqA0JpMk=
+golang.org/x/net v0.0.0-20220407224826-aac1ed45d8e3 h1:EN5+DfgmRMvRUrMGERW2gQl3Vc+Z7ZMnI/xdEpPSf0c=
+golang.org/x/net v0.0.0-20220407224826-aac1ed45d8e3/go.mod h1:CfG3xpIq0wQ8r1q4Su4UZFWDARRcnwPjda9FqA0JpMk=
 golang.org/x/sys v0.0.0-20201119102817-f84b799fce68/go.mod h1:h1NjWce9XRLGQEsW7wpKNCjG9DtNlClVuFLEZdDNbEs=
 golang.org/x/sys v0.0.0-20210423082822-04245dca01da/go.mod h1:h1NjWce9XRLGQEsW7wpKNCjG9DtNlClVuFLEZdDNbEs=
 golang.org/x/sys v0.0.0-20210615035016-665e8c7367d1/go.mod h1:oPkhp1MJrh7nUepCBck5+mAzfO9JrbApNNgaTdGDITg=
diff --git a/xmlChart.go b/xmlChart.go
index 45f1ce6..b6ee3cd 100644
--- a/xmlChart.go
+++ b/xmlChart.go
@@ -520,23 +520,23 @@ type cPageMargins struct {
 
 // formatChartAxis directly maps the format settings of the chart axis.
 type formatChartAxis struct {
-	None                bool    `json:"none"`
-	Crossing            string  `json:"crossing"`
-	MajorGridlines      bool    `json:"major_grid_lines"`
-	MinorGridlines      bool    `json:"minor_grid_lines"`
-	MajorTickMark       string  `json:"major_tick_mark"`
-	MinorTickMark       string  `json:"minor_tick_mark"`
-	MinorUnitType       string  `json:"minor_unit_type"`
-	MajorUnit           float64 `json:"major_unit"`
-	MajorUnitType       string  `json:"major_unit_type"`
-	TickLabelSkip       int     `json:"tick_label_skip"`
-	DisplayUnits        string  `json:"display_units"`
-	DisplayUnitsVisible bool    `json:"display_units_visible"`
-	DateAxis            bool    `json:"date_axis"`
-	ReverseOrder        bool    `json:"reverse_order"`
-	Maximum             float64 `json:"maximum"`
-	Minimum             float64 `json:"minimum"`
-	NumFormat           string  `json:"num_format"`
+	None                bool     `json:"none"`
+	Crossing            string   `json:"crossing"`
+	MajorGridlines      bool     `json:"major_grid_lines"`
+	MinorGridlines      bool     `json:"minor_grid_lines"`
+	MajorTickMark       string   `json:"major_tick_mark"`
+	MinorTickMark       string   `json:"minor_tick_mark"`
+	MinorUnitType       string   `json:"minor_unit_type"`
+	MajorUnit           float64  `json:"major_unit"`
+	MajorUnitType       string   `json:"major_unit_type"`
+	TickLabelSkip       int      `json:"tick_label_skip"`
+	DisplayUnits        string   `json:"display_units"`
+	DisplayUnitsVisible bool     `json:"display_units_visible"`
+	DateAxis            bool     `json:"date_axis"`
+	ReverseOrder        bool     `json:"reverse_order"`
+	Maximum             *float64 `json:"maximum"`
+	Minimum             *float64 `json:"minimum"`
+	NumFormat           string   `json:"num_format"`
 	NumFont             struct {
 		Color     string `json:"color"`
 		Bold      bool   `json:"bold"`
diff --git a/xmlWorksheet.go b/xmlWorksheet.go
index e4d52ec..eb855c5 100644
--- a/xmlWorksheet.go
+++ b/xmlWorksheet.go
@@ -116,7 +116,7 @@ type xlsxPageSetUp struct {
 	FirstPageNumber    string   `xml:"firstPageNumber,attr,omitempty"`
 	FitToHeight        *int     `xml:"fitToHeight,attr"`
 	FitToWidth         *int     `xml:"fitToWidth,attr"`
-	HorizontalDPI      float64  `xml:"horizontalDpi,attr,omitempty"`
+	HorizontalDPI      string   `xml:"horizontalDpi,attr,omitempty"`
 	RID                string   `xml:"http://schemas.openxmlformats.org/officeDocument/2006/relationships id,attr,omitempty"`
 	Orientation        string   `xml:"orientation,attr,omitempty"`
 	PageOrder          string   `xml:"pageOrder,attr,omitempty"`
@@ -126,7 +126,7 @@ type xlsxPageSetUp struct {
 	Scale              int      `xml:"scale,attr,omitempty"`
 	UseFirstPageNumber bool     `xml:"useFirstPageNumber,attr,omitempty"`
 	UsePrinterDefaults bool     `xml:"usePrinterDefaults,attr,omitempty"`
-	VerticalDPI        float64  `xml:"verticalDpi,attr,omitempty"`
+	VerticalDPI        string   `xml:"verticalDpi,attr,omitempty"`
 }
 
 // xlsxPrintOptions directly maps the printOptions element in the namespace