/*---------------------------
16Mar2010 - version 2.0

Curve Estimation

Author: Liu Wei, The School of Sociology and Population Studies, Renmin University of China
E-mail: rucwz-stata@yahoo.cn
---------------------------*/
capture prog drop curvefit
prog define curvefit, sortpreserve
	version 10.0
	syntax varlist(numeric max=2) [if] [in], Function(string) [Nograph Initial(string) Count(integer 4)]
	marksample touse
	tokenize `varlist'
	qui sort `2'
	qui est clear
	qui cap drop yhat*
	local fit_num=0
	local notfit_num=0
	local notfit=""
	qui {	
		if regexm("`function'","1") | regexm("`function'","ALL") {
			if "`initial'"=="" {
				cap nl (`1'= {b0} + ({b1} * (`2'))) if `touse', variables(`2') nolog
			}
			else {
				cap nl (`1'= {b0} + ({b1} * (`2'))) if `touse', variables(`2') nolog initial("`initial'")
			}
			if _rc==0 & e(r2_a)>0 {
				est sto Linear
				gen yhat_1=_coef[/b0]+(_coef[/b1]*(`2'))
				label var yhat_1 "Linear Fit"
				local fit_num=`fit_num'+1
			}
			else {
				local notfit="`notfit'"+"Linear "
				local notfit_num=`notfit_num'+1
			}
		}		
		if regexm("`function'","2") | regexm("`function'","ALL") {
			if "`initial'"=="" {
				cap nl (`1'= {b0} + ({b1} * ln((`2')))) if `touse', variables(`2') nolog
			}
			else {
				cap nl (`1'= {b0} + ({b1} * ln((`2')))) if `touse', variables(`2') nolog initial("`initial'")
			}
			if _rc==0 & e(r2_a)>0 {
				est sto Logarithmic
				gen yhat_2=_coef[/b0]+(_coef[/b1]*ln((`2')))
				label var yhat_2 "Logarithmic Fit"
				local fit_num=`fit_num'+1
			}
			else {
				local notfit="`notfit'"+"Logarithmic "
				local notfit_num=`notfit_num'+1
			}
		}
		if regexm("`function'","3") | regexm("`function'","ALL") {
			if "`initial'"=="" {
				cap nl (`1'= {b0} + ({b1} / (`2'))) if `touse', variables(`2') nolog
			}
			else {
				cap nl (`1'= {b0} + ({b1} / (`2'))) if `touse', variables(`2') nolog initial("`initial'")
			}
			if _rc==0 & e(r2_a)>0 {
				est sto Inverse
				gen yhat_3=_coef[/b0]+(_coef[/b1]/(`2'))
				label var yhat_3 "Inverse Fit"
				local fit_num=`fit_num'+1
			}
			else {
				local notfit="`notfit'"+"Inverse "
				local notfit_num=`notfit_num'+1
			}
		}
		if regexm("`function'","4") | regexm("`function'","ALL") {
			if "`initial'"=="" {
				cap nl (`1'= {b0} + ({b1} * (`2')) + ({b2} * (`2')^2)) if `touse', variables(`2') nolog
			}
			else {
				cap nl (`1'= {b0} + ({b1} * (`2')) + ({b2} * (`2')^2)) if `touse', variables(`2') nolog initial("`initial'")
			}
			if _rc==0 & e(r2_a)>0 {
				est sto Quadratic
				gen yhat_4=_coef[/b0]+(_coef[/b1]*(`2'))+(_coef[/b2]*(`2')^2)
				label var yhat_4 "Quadratic Fit"
				local fit_num=`fit_num'+1
			}
			else {
				local notfit="`notfit'"+"Quadratic "
				local notfit_num=`notfit_num'+1
			}
		}
		if regexm("`function'","5") | regexm("`function'","ALL") {
			if "`initial'"=="" {
				cap nl (`1'= {b0} + ({b1} * (`2')) + ({b2} * (`2')^2) + ({b3} * (`2')^3)) if `touse', variables(`2') nolog
			}
			else {
				cap nl (`1'= {b0} + ({b1} * (`2')) + ({b2} * (`2')^2) + ({b3} * (`2')^3)) if `touse', variables(`2') nolog initial("`initial'")
			}
			if _rc==0 & e(r2_a)>0 {
				est sto Cubic
				gen yhat_5=_coef[/b0]+(_coef[/b1]*(`2'))+(_coef[/b2]*(`2')^2)+(_coef[/b3]*(`2')^3)
				label var yhat_5 "Cubic Fit"
				local fit_num=`fit_num'+1
			}
			else {
				local notfit="`notfit'"+"Cubic "
				local notfit_num=`notfit_num'+1
			}
		}
		if regexm("`function'","6") | regexm("`function'","ALL") {
			if "`initial'"=="" {
				cap nl (`1'= {b0} * ((`2')^{b1})) if `touse', variables(`2') nolog
			}
			else {
				cap nl (`1'= {b0} * ((`2')^{b1})) if `touse', variables(`2') nolog initial("`initial'")
			}
			if _rc==0 & e(r2_a)>0 {
				est sto Power
				gen yhat_6=_coef[/b0]*((`2')^_coef[/b1])
				label var yhat_6 "Power Fit"
				local fit_num=`fit_num'+1
			}
			else {
				local notfit="`notfit'"+"Power "
				local notfit_num=`notfit_num'+1
			}
		}
		if regexm("`function'","7") | regexm("`function'","ALL") {
			if "`initial'"=="" {
				cap nl (`1'= {b0} * ({b1}^(`2'))) if `touse', variables(`2') nolog
			}
			else {
				cap nl (`1'= {b0} * ({b1}^(`2'))) if `touse', variables(`2') nolog initial("`initial'")
			}
			if _rc==0 & e(r2_a)>0 {
				est sto Compound
				gen yhat_7=_coef[/b0]*(_coef[/b1]^(`2'))
				label var yhat_7 "Compound Fit"
				local fit_num=`fit_num'+1
			}
			else {
				local notfit="`notfit'"+"Compound "
				local notfit_num=`notfit_num'+1
			}
		}
		if regexm("`function'","8") | regexm("`function'","ALL") {
			if "`initial'"=="" {
				cap nl (`1'= exp({b0} + ({b1}/(`2')))) if `touse', variables(`2') nolog
			}
			else {
				cap nl (`1'= exp({b0} + ({b1}/(`2')))) if `touse', variables(`2') nolog initial("`initial'")
			}
			if _rc==0 & e(r2_a)>0 {
				est sto S_curve
				gen yhat_8=exp(_coef[/b0]+(_coef[/b1]/(`2')))
				label var yhat_8 "S_curve Fit"
				local fit_num=`fit_num'+1
			}
			else {
				local notfit="`notfit'"+"S_curve "
				local notfit_num=`notfit_num'+1
			}
		}
		if regexm("`function'","9") | regexm("`function'","ALL") {
			if "`initial'"=="" {
				cap nl (`1'= {b0} / (1 + {b1} * exp(-{b2} * (`2')))) if `touse', variables(`2') nolog
			}
			else {
				cap nl (`1'= {b0} / (1 + {b1} * exp(-{b2} * (`2')))) if `touse', variables(`2') nolog initial("`initial'")
			}
			if _rc==0 & e(r2_a)>0 {
				est sto Logistic
				gen yhat_9= _coef[/b0] / (1 + _coef[/b1] * exp(-_coef[/b2] * (`2')))
				label var yhat_9 "Logistic Model"
				local fit_num=`fit_num'+1
			}
			else {
				local notfit="`notfit'"+"Logistic "
				local notfit_num=`notfit_num'+1
			}
		}
		if regexm("`function'","0") | regexm("`function'","ALL") {
			if "`initial'"=="" {
				cap nl (`1'= exp({b0} + ({b1} * (`2')))) if `touse', variables(`2') nolog
			}
			else {
				cap nl (`1'= exp({b0} + ({b1} * (`2')))) if `touse', variables(`2') nolog initial("`initial'")
			}
			if _rc==0 & e(r2_a)>0 {
				est sto Growth
				gen yhat_0 = exp(_coef[/b0]+(_coef[/b1]*(`2')))
				label var yhat_0 "Growth Fit"
				local fit_num=`fit_num'+1
			}
			else {
				local notfit="`notfit'"+"Growth "
				local notfit_num=`notfit_num'+1
			}
		}
		if regexm("`function'","a") | regexm("`function'","ALL") {
			if "`initial'"=="" {
				cap nl (`1'= {b0} * (exp({b1} * (`2')))) if `touse', variables(`2') nolog
			}
			else {
				cap nl (`1'= {b0} * (exp({b1} * (`2')))) if `touse', variables(`2') nolog initial("`initial'")
			}
			if _rc==0 & e(r2_a)>0 {
				est sto Exponential
				gen yhat_a=_coef[/b0]*(exp(_coef[/b1]*(`2')))
				label var yhat_a "Exponential Fit"
				local fit_num=`fit_num'+1
			}
			else {
				local notfit="`notfit'"+"Exponential "
				local notfit_num=`notfit_num'+1
			}
		}
		if regexm("`function'","b") | regexm("`function'","ALL") {			
			if "`initial'"=="" {
				cap nl (`1' = exp({b0} + {b1}/(`2')+{b2} * ln((`2')))) if `touse', variables(`2') nolog
			}
			else {
				cap nl (`1' = exp({b0} + {b1}/(`2')+{b2} * ln((`2')))) if `touse', variables(`2') nolog initial("`initial'")
			}
			if _rc==0 & e(r2_a)>0 {
				est sto Vapor_Pressure
				gen yhat_b=exp(_coef[/b0] + _coef[/b1]/(`2')+_coef[/b2] * ln((`2')))
				label var yhat_b "Vapor Pressure Model"
				local fit_num=`fit_num'+1
			}
			else {
				local notfit="`notfit'"+"Vapor_Pressure "
				local notfit_num=`notfit_num'+1
			}
		}
		if regexm("`function'","c") | regexm("`function'","ALL") {
			if "`initial'"=="" {
				cap nl (`1'=1/ ({b0} + ({b1} * ln((`2'))))) if `touse', variables(`2') nolog
			}
			else {
				cap nl (`1'=1/ ({b0} + ({b1} * ln((`2'))))) if `touse', variables(`2') nolog initial("`initial'")
			}
			if _rc==0 & e(r2_a)>0 {
				est sto R_Logarithmic
				gen yhat_c=1/(_coef[/b0]+(_coef[/b1]*ln((`2'))))
				label var yhat_c "Reciprocal Logarithmic Fit"
				local fit_num=`fit_num'+1
			}
			else {
				local notfit="`notfit'"+"R_Logarithmic "
				local notfit_num=`notfit_num'+1
			}
		}
		if regexm("`function'","d") | regexm("`function'","ALL") {
			if "`initial'"=="" {
				cap nl (`1'={b0} * {b1}^(`2')) if `touse', variables(`2') nolog
			}
			else {
				cap nl (`1'={b0} * {b1}^(`2')) if `touse', variables(`2') nolog initial("`initial'")
			}
			if _rc==0 & e(r2_a)>0 {
				est sto M_Power
				gen yhat_d=_coef[/b0] * _coef[/b1]^(`2')
				label var yhat_d "Modified Power Fit"
				local fit_num=`fit_num'+1
			}
			else {
				local notfit="`notfit'"+"M_Power "
				local notfit_num=`notfit_num'+1
			}
		}
		if regexm("`function'","e") | regexm("`function'","ALL") {
			if "`initial'"=="" {
				cap nl (`1'= {b0} * ((`2') - {b1})^{b3}) if `touse', variables(`2') nolog
			}
			else {
				cap nl (`1'= {b0} * ((`2') - {b1})^{b3}) if `touse', variables(`2') nolog initial("`initial'")
			}
			if _rc==0 & e(r2_a)>0 {
				est sto Shifted_Power
				gen yhat_e=_coef[/b0] * ((`2') - _coef[/b1])^_coef[/b3]
				label var yhat_e "Shifted Power Fit"
				local fit_num=`fit_num'+1
			}
			else {
				local notfit="`notfit'"+"Shifted_Power "
				local notfit_num=`notfit_num'+1
			}
		}		
		if regexm("`function'","f") | regexm("`function'","ALL") {
			if "`initial'"=="" {
				cap nl (`1'= {b0} * (`2')^({b1} * (`2'))) if `touse', variables(`2') nolog
			}
			else {
				cap nl (`1'= {b0} * (`2')^({b1} * (`2'))) if `touse', variables(`2') nolog initial("`initial'")
			}
			if _rc==0 & e(r2_a)>0 {
				est sto Geometric
				gen yhat_f= _coef[/b0] * (`2')^(_coef[/b1] * (`2'))
				label var yhat_f "Geometric Fit"
				local fit_num=`fit_num'+1
			}
			else {
				local notfit="`notfit'"+"Geometric "
				local notfit_num=`notfit_num'+1
			}
		}
		if regexm("`function'","g") | regexm("`function'","ALL") {
			if "`initial'"=="" {
				cap nl (`1'= {b0} * (`2')^({b1}/(`2'))) if `touse', variables(`2') nolog
			}
			else {
				cap nl (`1'= {b0} * (`2')^({b1}/(`2'))) if `touse', variables(`2') nolog initial("`initial'")
			}
			if _rc==0 & e(r2_a)>0 {
				est sto M_Geometric
				gen yhat_g=_coef[/b0] * (`2')^(_coef[/b1]/(`2'))
				label var yhat_g "Modified Geometric Fit"
				local fit_num=`fit_num'+1
			}
			else {
				local notfit="`notfit'"+"M_Geometric "
				local notfit_num=`notfit_num'+1
			}
		}
		if regexm("`function'","h") | regexm("`function'","ALL") {
			local equa1="{b0}"
			local equa2="_coef[/b0]"
			forv i=1/`count' {
				local equa1="`equa1'"+"+"+"{b`i'}"+"*"+"(`2')^`i'"
				local equa2="`equa2'"+"+"+"_coef[/b`i']"+"*"+"(`2')^`i'"
			}
			if "`initial'"=="" {
				nl (`1'= `equa1') if `touse', variables(`2') nolog
			}
			else {
				cap nl (`1'= `equa1') if `touse', variables(`2') nolog initial("`initial'")
			}
			if _rc==0 & e(r2_a)>0 {
				est sto Polynomial
				gen yhat_h=`equa2'
				label var yhat_h "`count' order Polynomial Fit"
				local fit_num=`fit_num'+1
			}
			else {
				local notfit="`notfit'"+"Polynomial "
				local notfit_num=`notfit_num'+1
			}
		}			
		if regexm("`function'","i") | regexm("`function'","ALL") {
			if "`initial'"=="" {
				cap nl (`1'= {b0} * ({b1}^(`2')) * ((`2')^{b2})) if `touse', variables(`2') nolog
			}
			else {
				cap nl (`1'= {b0} * ({b1}^(`2')) * ((`2')^{b2})) if `touse', variables(`2') nolog initial("`initial'")
			}
			if _rc==0 & e(r2_a)>0 {
				est sto Hoerl
				gen yhat_i=_coef[/b0] * (_coef[/b1]^(`2')) * ((`2')^_coef[/b2])
				label var yhat_i "Hoerl Model"
				local fit_num=`fit_num'+1
			}
			else {
				local notfit="`notfit'"+"Hoerl "
				local notfit_num=`notfit_num'+1
			}
		}
		if regexm("`function'","j") | regexm("`function'","ALL") {
			if "`initial'"=="" {
				cap nl (`1'= {b0} * {b1}^(1/(`2')) * ((`2')^{b2})) if `touse', variables(`2') nolog
			}
			else {
				cap nl (`1'= {b0} * {b1}^(1/(`2')) * ((`2')^{b2})) if `touse', variables(`2') nolog initial("`initial'")
			}
			if _rc==0 & e(r2_a)>0 {
				est sto M_Hoerl
				gen yhat_j=_coef[/b0] * _coef[/b1]^(1/(`2')) * ((`2')^_coef[/b2])
				label var yhat_j "Modified Hoerl Model"
				local fit_num=`fit_num'+1
			}
			else {
				local notfit="`notfit'"+"M_Hoerl "
				local notfit_num=`notfit_num'+1
			}
		}
		if regexm("`function'","k") | regexm("`function'","ALL") {
			if "`initial'"=="" {
				cap nl (`1'= 1 / ({b0} + {b1} * (`2'))) if `touse', variables(`2') nolog
			}
			else {
				cap nl (`1'= 1 / ({b0} + {b1} * (`2'))) if `touse', variables(`2') nolog initial("`initial'")
			}
			if _rc==0 & e(r2_a)>0 {
				est sto Reciprocal
				gen yhat_k=1 / (_coef[/b0] + _coef[/b1] * (`2'))
				label var yhat_k "Reciprocal Model"
				local fit_num=`fit_num'+1
			}
			else {
				local notfit="`notfit'"+"Reciprocal "
				local notfit_num=`notfit_num'+1
			}
		}
		if regexm("`function'","l") | regexm("`function'","ALL") {
			if "`initial'"=="" {
				cap nl (`1'= 1 / ({b0} + {b1} * (`2') + {b2} * (`2')^2)) if `touse', variables(`2') nolog
			}
			else {
				cap nl (`1'= 1 / ({b0} + {b1} * (`2') + {b2} * (`2')^2)) if `touse', variables(`2') nolog initial("`initial'")
			}
			if _rc==0 & e(r2_a)>0 {
				est sto R_Quadratic
				gen yhat_l=1 / (_coef[/b0] + _coef[/b1] * (`2') + _coef[/b2] * (`2')^2)
				label var yhat_l "Reciprocal Quadratic Model"
				local fit_num=`fit_num'+1
			}
			else {
				local notfit="`notfit'"+"R_Quadratic "
				local notfit_num=`notfit_num'+1
			}
		}
		if regexm("`function'","m") | regexm("`function'","ALL") {
			if "`initial'"=="" {
				cap nl (`1'= ({b0} + {b1} * (`2'))^(-1 / {b2})) if `touse', variables(`2') nolog
			}
			else {
				cap nl (`1'= ({b0} + {b1} * (`2'))^(-1 / {b2})) if `touse', variables(`2') nolog initial("`initial'")
			}
			if _rc==0 & e(r2_a)>0 {
				est sto Bleasdale
				gen yhat_m=(_coef[/b0] + _coef[/b1] * (`2'))^(-1 / _coef[/b2])
				label var yhat_m "Bleasdale Model"
				local fit_num=`fit_num'+1
			}
			else {
				local notfit="`notfit'"+"Bleasdale "
				local notfit_num=`notfit_num'+1
			}
		}
		if regexm("`function'","n") | regexm("`function'","ALL") {
			if "`initial'"=="" {
				cap nl (`1'= 1 / ({b0} + {b1} * (`2')^{b2})) if `touse', variables(`2') nolog
			}
			else {
				cap nl (`1'= 1 / ({b0} + {b1} * (`2')^{b2})) if `touse', variables(`2') nolog initial("`initial'")
			}
			if _rc==0 & e(r2_a)>0 {
				est sto Harris
				gen yhat_n=1 / (_coef[/b0] + _coef[/b1] * (`2')^_coef[/b2])
				label var yhat_n "Harris Model"
				local fit_num=`fit_num'+1
			}
			else {
				local notfit="`notfit'"+"Harris "
				local notfit_num=`notfit_num'+1
			}
		}
		if regexm("`function'","o") | regexm("`function'","ALL") {
			if "`initial'"=="" {
				cap nl (`1'= {b0} * (1 - exp(-{b1} * (`2')))) if `touse', variables(`2') nolog
			}
			else {
				cap nl (`1'= {b0} * (1 - exp(-{b1} * (`2')))) if `touse', variables(`2') nolog initial("`initial'")
			}
			if _rc==0 & e(r2_a)>0 {
				est sto Exp_Association
				gen yhat_o=_coef[/b0] * (1 - exp(-_coef[/b1] * (`2')))
				label var yhat_o "Exponential Association Fit"
				local fit_num=`fit_num'+1
			}
			else {
				local notfit="`notfit'"+"Exp_Association "
				local notfit_num=`notfit_num'+1
			}
		}
		if regexm("`function'","p") | regexm("`function'","ALL") {
			if "`initial'"=="" {
				cap nl (`1'= {b0} * ({b1} - exp(-{b2} * (`2')))) if `touse', variables(`2') nolog
			}
			else {
				cap nl (`1'= {b0} * ({b1} - exp(-{b2} * (`2')))) if `touse', variables(`2') nolog initial("`initial'")
			}
			if _rc==0 & e(r2_a)>0 {
				est sto Thr_Para_Exp_Association
				gen yhat_p=_coef[/b0] * (_coef[/b1] - exp(-_coef[/b2] * (`2')))
				label var yhat_p "Three-Parameter Exponential Association Fit"
				local fit_num=`fit_num'+1
			}
			else {
				local notfit="`notfit'"+"Thr_Para_Exp_Association "
				local notfit_num=`notfit_num'+1
			}
		}
		if regexm("`function'","q") | regexm("`function'","ALL") {
			if "`initial'"=="" {
				cap nl (`1'= {b0} * (`2')/({b1} + (`2'))) if `touse', variables(`2') nolog
			}
			else {
				cap nl (`1'= {b0} * (`2')/({b1} + (`2'))) if `touse', variables(`2') nolog initial("`initial'")
			}
			if _rc==0 & e(r2_a)>0 {
				est sto Saturation_Growth_Rate
				gen yhat_q=_coef[/b0] * (`2')/(_coef[/b1] + (`2'))
				label var yhat_q "Saturation-Growth Rate Model"
				local fit_num=`fit_num'+1
			}
			else {
				local notfit="`notfit'"+"Saturation_Growth_Rate "
				local notfit_num=`notfit_num'+1
			}
		}		
		if regexm("`function'","r") | regexm("`function'","ALL") {
			if "`initial'"=="" {
				cap nl (`1'= {b0} * exp(-exp({b1} - {b2} * (`2')))) if `touse', variables(`2') nolog
			}
			else {
				cap nl (`1'= {b0} * exp(-exp({b1} - {b2} * (`2')))) if `touse', variables(`2') nolog initial("`initial'")
			}
			if _rc==0 & e(r2_a)>0 {
				est sto Gompertz_Relation
				gen yhat_r=_coef[/b0] * exp(-exp(_coef[/b1] - _coef[/b2] * (`2')))
				label var yhat_r "Gompertz Relation Model"
				local fit_num=`fit_num'+1
			}
			else {
				local notfit="`notfit'"+"Gompertz_Relation "
				local notfit_num=`notfit_num'+1
			}
		}
		if regexm("`function'","s") | regexm("`function'","ALL") {
			if "`initial'"=="" {
				cap nl (`1'= {b0} / (1 + exp({b1} - {b2} * (`2')))^(1/{b3})) if `touse', variables(`2') nolog
			}
			else {
				cap nl (`1'= {b0} / (1 + exp({b1} - {b2} * (`2')))^(1/{b3})) if `touse', variables(`2') nolog initial("`initial'")
			}
			if _rc==0 & e(r2_a)>0 {
				est sto Richards
				gen yhat_s=_coef[/b0] / (1 + exp(_coef[/b1] - _coef[/b2] * (`2')))^(1/_coef[/b3])
				label var yhat_s "Richards Model"
				local fit_num=`fit_num'+1
			}
			else {
				local notfit="`notfit'"+"Richards "
				local notfit_num=`notfit_num'+1
			}
		}
		if regexm("`function'","ALL") | regexm("`function'","ALL") {
			if "`initial'"=="" {
				cap nl (`1'= ({b0} * {b1}+{b2} * (`2')^{b3})/({b1} + (`2')^{b3})) if `touse', variables(`2') nolog
			}
			else {
				cap nl (`1'= ({b0} * {b1}+{b2} * (`2')^{b3})/({b1} + (`2')^{b3})) if `touse', variables(`2') nolog initial("`initial'")
			}
			if _rc==0 & e(r2_a)>0 {
				est sto MMF
				gen yhat_t=(_coef[/b0] * _coef[/b1]+_coef[/b2] * (`2')^_coef[/b3])/(_coef[/b1] + (`2')^_coef[/b3])
				label var yhat_t "MMF Model"
				local fit_num=`fit_num'+1
			}
			else {
				local notfit="`notfit'"+"MMF "
				local notfit_num=`notfit_num'+1
			}
		}
		if regexm("`function'","u") | regexm("`function'","ALL") {
			if "`initial'"=="" {
				cap nl (`1'= {b0} - {b1}*exp(-{b2} * (`2')^{b3})) if `touse', variables(`2') nolog
			}
			else {
				cap nl (`1'= {b0} - {b1}*exp(-{b2} * (`2')^{b3})) if `touse', variables(`2') nolog initial("`initial'")
			}
			if _rc==0 & e(r2_a)>0 {
				est sto Weibull
				gen yhat_u=_coef[/b0] - _coef[/b1]*exp(-_coef[/b2] * (`2')^_coef[/b3])
				label var yhat_u "Weibull Model"
				local fit_num=`fit_num'+1
			}
			else {
				local notfit="`notfit'"+"Weibull "
				local notfit_num=`notfit_num'+1
			}
		}
		if regexm("`function'","v") | regexm("`function'","ALL") {
			if "`initial'"=="" {
				cap nl (`1'= {b0}+{b1} * {b2} * cos({b2} * (`2') + {b3})) if `touse', variables(`2') nolog
			}
			else {
				cap nl (`1'= {b0}+{b1} * {b2} * cos({b2} * (`2') + {b3})) if `touse', variables(`2') nolog initial("`initial'")
			}
			if _rc==0 & e(r2_a)>0 {
				est sto Sinusoida
				gen yhat_v=_coef[/b0]+_coef[/b1] * _coef[/b2] * cos(_coef[/b2] * (`2') + _coef[/b3])
				label var yhat_v "Sinusoida Function"
				local fit_num=`fit_num'+1
			}
			else {
				local notfit="`notfit'"+"Sinusoida "
				local notfit_num=`notfit_num'+1
			}
		}
		if regexm("`function'","w") | regexm("`function'","ALL") {
			if "`initial'"=="" {
				cap nl (`1'= {b0} * exp((-({b1} - (`2'))^2)/(2 * {b2}^2))) if `touse', variables(`2') nolog
			}
			else {
				cap nl (`1'= {b0} * exp((-({b1} - (`2'))^2)/(2 * {b2}^2))) if `touse', variables(`2') nolog initial("`initial'")
			}
			if _rc==0 & e(r2_a)>0 {
				est sto Gaussian
				gen yhat_w=_coef[/b0] * exp((-(_coef[/b1] - (`2'))^2)/(2 * _coef[/b2]^2))
				label var yhat_w "Gaussian Model"
				local fit_num=`fit_num'+1
			}
			else {
				local notfit="`notfit'"+"Gaussian "
				local notfit_num=`notfit_num'+1
			}
		}
		if regexm("`function'","x") | regexm("`function'","ALL") {
			if "`initial'"=="" {
				cap nl (`1'= {b0} + {b1} * (`2') + {b2}/(`2')^2) if `touse', variables(`2') nolog
			}
			else {
				cap nl (`1'= {b0} + {b1} * (`2') + {b2}/(`2')^2) if `touse', variables(`2') nolog initial("`initial'")
			}
			if _rc==0 & e(r2_a)>0 {
				est sto Heat_Capacity
				gen yhat_x=_coef[/b0] + _coef[/b1] * (`2') + _coef[/b2]/(`2')^2
				label var yhat_x "Heat Capacity Model"
				local fit_num=`fit_num'+1
			}
			else {
				local notfit="`notfit'"+"Heat_Capacity "
				local notfit_num=`notfit_num'+1
			}
		}
		if regexm("`function'","y") | regexm("`function'","ALL") {
			if "`initial'"=="" {
				cap nl (`1'= ({b0} + {b1} * (`2'))/(1 + {b2} * (`2') + {b3} * (`2')^2)) if `touse', variables(`2') nolog
			}
			else {
				cap nl (`1'= ({b0} + {b1} * (`2'))/(1 + {b2} * (`2') + {b3} * (`2')^2)) if `touse', variables(`2') nolog initial("`initial'")
			}
			if _rc==0 & e(r2_a)>0 {
				est sto Rational
				gen yhat_y=(_coef[/b0] + _coef[/b1] * (`2'))/(1 + _coef[/b2] * (`2') + _coef[/b3] * (`2')^2)
				label var yhat_y "Rational Function"
				local fit_num=`fit_num'+1
			}
			else {
				local notfit="`notfit'"+"Rational "
				local notfit_num=`notfit_num'+1
			}
		}
	}
	
	if `fit_num'>0 {
		estimates table *,  stats(N r2_a) t p modelwidth(11) title(Curve Estimation between "`1'" and "`2'")
		label var `1' "Observed"
		if "`nograph'"=="" {
			twoway (scatter `1' `2') (line yhat* `2'), title(Curve fit for `1') legend(cols(1) colgap(tiny) size(small) region(lcolor(none)) position(3))	
		}
	}
	qui est clear
	if `notfit_num'>0 {
		di _n as erro "Note: " as txt "Models of " as result "`notfit'" as txt "erro setting or not fit the data!"
	}
	
end