Merge remote-tracking branch 'origin/master'

26 files changed, 447 insertions, 16 deletions

diff --git a/101/Makefile b/101/Makefile
new file mode 100644
index 0000000..eb309ff
--- /dev/null
+++ b/101/Makefile
@@ -0,0 +1,18 @@
+
+CFLAGS = -std=c++2c -mavx -Iinclude -ggdb
+
+.PHONY: all run_main clean gnuplot 
+
+run: gnuplot
+
+gnuplot: plots.gp run_main
+	gnuplot $<
+
+run_main: main
+	./main
+
+main: main.cpp include/*
+	$(CXX) -o $@ $< $(CFLAGS)
+
+clean: 
+	rm -fr main *.png *.plot
diff --git a/101/README.md b/101/README.md
new file mode 100644
index 0000000..96fd716
--- /dev/null
+++ b/101/README.md
@@ -0,0 +1,5 @@
+<!-- Шаблон для прака -->
+<!-- файлы, заканчивающиеся на .plot считаются генерируемыми и удаляются через make clean -->
+# Обработка <> прака
+
+
diff --git a/101/compile_flags.txt b/101/compile_flags.txt
new file mode 100644
index 0000000..34ae930
--- /dev/null
+++ b/101/compile_flags.txt
@@ -0,0 +1,4 @@
+-Iinclude
+-std=c++2c
+-mavx2
+
diff --git a/101/ex1 b/101/ex1
new file mode 100644
index 0000000..6c38a0b
--- /dev/null
+++ b/101/ex1
@@ -0,0 +1,11 @@
+N	a1		a2		a3		a	sa	acal	sacal
+1	0.13346		0.13171		0.132942	?	?	?	?
+2	0.282912	0.282706	0.28394		?	?	?	?
+3	0.429228	0.428942	0.429562	?	?	?	?
+4	0.569562	0.567884	0.56956		?	?	?	?
+5	0.7058		0.704906	0.70637		?	?	?	?
+6	0.838736	0.821824	0.84288		?	?	?	?
+7	0.969494	0.967614	0.9688		?	?	?	?
+8	1.095644	1.094602	1.094976	?	?	?	?
+9	1.217494	1.21835		1.219444	?	?	?	?
+10	1.33011		1.324222	1.335216	?	?	?	?
diff --git a/101/ex2 b/101/ex2
new file mode 100644
index 0000000..c6750fc
--- /dev/null
+++ b/101/ex2
@@ -0,0 +1,11 @@
+N	m1	m2	a1		a2		a3		a
+1	?	?	0.133954	0.132362	0.135396	?
+2	?	?	0.125120	0.129666	0.129296	?
+3	?	?	0.121898	0.123508	0.122264	?
+4	?	?	0.119830	0.119476	0.116626	?
+5	?	?	0.110080	0.111944	0.112238	?
+6	?	?	0.108780	0.111320	0.110016	?
+7	?	?	0.108712	0.106222	0.107966	?
+8	?	?	0.104368	0.105308	0.105832	?
+9	?	?	0.099952	0.102050	0.101092	?
+10	?	?	0.100834	0.100822	0.101342	?
diff --git a/101/ex3 b/101/ex3
new file mode 100644
index 0000000..6b37ca3
--- /dev/null
+++ b/101/ex3
@@ -0,0 +1,11 @@
+N	m1	m2	dm	a1		a2		a3		a
+1	?	?	?	0.101242	0.100606	0.100698	?
+2	?	?	?	0.324394	0.343446	0.345500	?
+3	?	?	?	0.587238	0.587220	0.564608	?
+4	?	?	?	0.828416	0.830074	0.815484	?
+5	?	?	?	1.063504	1.071230	1.070982	?
+6	?	?	?	1.305656	1.305208	1.307460 	?
+7	?	?	?	1.550900	1.548880	1.550336	?
+8	?	?	?	1.794500	1.792756	1.788620	?
+9	?	?	?	2.032050	2.032032	2.034266	?
+10	?	?	?	2.269558	2.272532	2.273842	?
diff --git a/101/include b/101/include
new file mode 120000
index 0000000..2225752
--- /dev/null
+++ b/101/include
@@ -0,0 +1 @@
+../libprakpp/include/
\ No newline at end of file
diff --git a/101/main b/101/main
new file mode 100755
index 0000000..cb77291
--- /dev/null
+++ b/101/main
diff --git a/101/main.cpp b/101/main.cpp
new file mode 100644
index 0000000..54d956d
--- /dev/null
+++ b/101/main.cpp
@@ -0,0 +1,137 @@
+#include <iostream>
+
+#include "include/praktable.hpp"
+
+using table = prak::table<f64>;
+using vecarg = const std::vector<f64> &;
+using f64v = std::vector<f64>;
+using f64p = prak::pvalue<f64>;
+
+const f64 g = 9.81571; // moscow local acceleration
+const f64 m_0 = 113.63 / 1000.0;
+const f64 m_s = 0.01 / 1000.0;
+
+f64p avg_mass(void) {
+	std::ifstream f("mass");
+	f64 acc = 0;
+	u32 cnt = 0;
+	for (f64 tmp; f >> tmp; acc += tmp, ++cnt);
+	f64 avg = acc / cnt;
+	f.clear();
+	f.seekg(0, std::ios::beg);
+	f64 stddev_acc = 0;
+	for (f64 tmp; f >> tmp; stddev_acc += (tmp-avg)*(tmp-avg));
+	return {.val = avg / 1000.0, .err = std::sqrt(stddev_acc / cnt / (cnt - 1)) / 1000.0};
+}
+
+// args[0] = dm
+// args[1] = m
+f64 acal(vecarg args) {
+	return g * args[0] / args[1];
+}
+
+f64 get_g(vecarg args) {
+	f64 C = args[0],
+	    m_bl = args[1],
+	    m = args[2],
+	    m0 = args[3],
+	    a = args[4];
+	return C * (a*m_bl + m + m0);
+}
+
+f64 get_M(vecarg args) {
+	f64 D = args[0],
+	    m_bl = args[1],
+	    m = args[2],
+	    m0 = args[3],
+	    a = args[4],
+	    R = args[5];
+	return D * (a*m_bl + m + m0) * R;
+}
+
+void ex1(f64p m) {
+	table t("ex1");
+	t	.apply(prak::avg<f64>, {"a1", "a2", "a3"}, "a")
+		.apply(prak::stddev<f64>, {"a1", "a2", "a3"}, "sa")
+		.apply([m](vecarg arg) -> f64 { 
+			return acal({arg[0] * m.val, (m_0 + arg[0]*m.val)}); 
+		}, {"N"}, "acal")
+		.apply([m](vecarg arg) -> f64 {
+			f64v args = {arg[0] * m.val, m_0 + arg[0]*m.val};
+			f64v sigmas = {m.err * arg[0], m_s};
+			return prak::sigma<f64>(acal, args, sigmas);
+		}, {"N"}, "sacal");
+	t.write_plot("ex1_exp.plot", "N", "a", "sa");
+	t.write_plot("ex1_calc.plot", "N", "acal", "sacal");
+	std::cout << "Упражнение 1: " << t << std::endl;
+}
+
+void ex2(f64p m) {
+	table in("ex2");
+	in	.apply([m] (vecarg a) {	return m.val * (a[0] - 1);	}, {"N"}, "m1")
+		.apply([m] (vecarg a) {	return m.val * a[0];		}, {"N"}, "m2")
+		.apply(prak::avg<f64>, {"a1", "a2", "a3"}, "a");
+	table out({"N", "M", "1/M", "a_exp", "a_cal", "da(%)"}, in.rows, NAN); 
+	{
+		int N = 0;
+		for (auto it = out.begin("N"); it != out.end("N"); ++it) *it = ++N;
+		for (size_t i = 0; i < in.rows; ++i) out["a_exp", i] = in["a", i];
+		out	.apply([m] (vecarg a) { return 	(2*a[0] - 1)*m.val + m_0;	}, {"N"}, "M")
+			.apply([m] (vecarg a) { return 	acal({m.val, a[0]});		}, {"M"}, "a_cal")
+			.apply([ ] (vecarg a) { return 	std::abs(a[0]-a[1])/a[0]*100;	}, {"a_cal", "a_exp"}, "da(%)")
+			.apply([ ] (vecarg a) { return 	1.0/a[0];			}, {"M"}, "1/M");
+	}
+	std::cout << "Таблица 3: " << in << "\nТаблица 4: " << out << std::endl;
+	
+	out.write_plot("ex2_exp.plot", "1/M", "a_exp", std::nullopt);
+	out.write_plot("ex2_cal.plot", "1/M", "a_cal", std::nullopt);
+	out.write_plot("ex2_dev.plot", "1/M", "da(%)", std::nullopt);
+}
+
+void ex3(f64p m) {
+	table in("ex3");
+	in	.apply([m] (vecarg a) { return	(10 - a[0]) * m.val;	}, {"N"}, "m1")
+		.apply([m] (vecarg a) { return	( 9 + a[0]) * m.val;	}, {"N"}, "m2")
+		.apply([m] (vecarg a) { return	(2 * a[0] - 1) * m.val;	}, {"N"}, "dm")
+		.apply(prak::avg<f64>, {"a1", "a2", "a3"}, "a");
+	in.add_column("sa", {});
+	in.apply(prak::stddev<f64>, {"a1", "a2", "a3"}, "sa");
+	table out({"N", "dm", "M", "1/M", "a_exp", "a_cal", "da(%)"}, in.rows, NAN);
+	{
+		int N = 0;
+		for (auto it = out.begin("N"); it != out.end("N"); ++it) *it = ++N;
+		for (size_t i = 0; i < in.rows; ++i) out["a_exp", i] = in["a", i];
+		out.fill_column("M", 19 * m.val + m_0);
+		out	.apply([m] (vecarg a) {	return	(2 * a[0] - 1) * m.val;		}, {"N"}, "dm")
+			.apply([ ] (vecarg a) { return 	acal({a[0], a[1]});		}, {"dm", "M"}, "a_cal")
+			.apply([ ] (vecarg a) { return 	std::abs(a[0]-a[1])/a[0]*100;	}, {"a_cal", "a_exp"}, "da(%)")
+			.apply([ ] (vecarg a) { return 	1.0/a[0];			}, {"M"}, "1/M");
+	}
+	std::cout << "Таблица 5: " << in << "\nТаблица 6: " << out << std::endl;
+	out.write_plot("ex3_exp.plot", "dm", "a_exp", std::nullopt);
+	out.write_plot("ex3_cal.plot", "dm", "a_cal", std::nullopt);
+	out.write_plot("ex3_dev.plot", "dm", "da(%)", std::nullopt);
+	auto [C, D] = out.least_squares_linear("dm", "a_exp", std::nullopt, in.col_avg("sa"));
+	f64p g, M;
+	f64v g_args	= {C.val, 0.0175, m.val * 19, m_0, 0.3},
+	     g_sigmas	= {C.err, 0.0005, m.err * 19, m_s, 0.1};
+	g.val = get_g(g_args);
+	g.err = prak::sigma<f64>(get_g, g_args, g_sigmas);
+	f64v M_args	= {D.val, 0.0175, m.val * 19, m_0, 0.3, 0.025},
+	     M_sigmas	= {D.err, 0.0005, m.err * 19, m_s, 0.0, 0.001};
+	M.val = get_M(M_args);
+	M.err = prak::sigma<f64>(get_M, M_args, M_sigmas);
+	std::cout << "Результаты регрессии:\n\tC = " << C << "\tD = " << D << '\n'
+		  << "Полученное значение g:\n\tg = " << g << '\n'
+		  << "Полученное значение M:\n\tM = " << M << std::endl;
+}
+
+int main() {
+	f64p m = avg_mass();
+	std::cout << "Средняя масса = " << m << std::endl;
+	ex1(m);
+	ex2(m);
+	ex3(m);
+
+	return 0;
+}
diff --git a/101/mass b/101/mass
new file mode 100644
index 0000000..2e48479
--- /dev/null
+++ b/101/mass
@@ -0,0 +1,20 @@
+1.88
+1.87
+1.87
+1.85
+1.86
+1.88
+1.88
+1.88
+1.88
+1.87
+1.87
+1.88
+1.88
+1.89
+1.89
+1.89
+1.86
+1.86
+1.86
+1.86
diff --git a/101/plots.gp b/101/plots.gp
new file mode 100644
index 0000000..702408a
--- /dev/null
+++ b/101/plots.gp
@@ -0,0 +1,14 @@
+set term pngcairo size 1000, 800
+set tmargin at screen 0.95
+
+f1(x) = a1*x+b1
+fit f1(x) '.plot' using 1:2:3 yerr via a1, b1
+
+set output ''
+set label "" at graph 0.5, graph 1.025 center
+set xlabel ""
+set ylabel ""
+
+plot 	'.plot' using 1:2:3 with yerrorbars notitle lc 0 pt 1 lw 2,	\
+	f1(x) title "" lc rgb "red",				\
+
diff --git a/107/Makefile b/107/Makefile
new file mode 100644
index 0000000..eb309ff
--- /dev/null
+++ b/107/Makefile
@@ -0,0 +1,18 @@
+
+CFLAGS = -std=c++2c -mavx -Iinclude -ggdb
+
+.PHONY: all run_main clean gnuplot 
+
+run: gnuplot
+
+gnuplot: plots.gp run_main
+	gnuplot $<
+
+run_main: main
+	./main
+
+main: main.cpp include/*
+	$(CXX) -o $@ $< $(CFLAGS)
+
+clean: 
+	rm -fr main *.png *.plot
diff --git a/107/README.md b/107/README.md
new file mode 100644
index 0000000..96fd716
--- /dev/null
+++ b/107/README.md
@@ -0,0 +1,5 @@
+<!-- Шаблон для прака -->
+<!-- файлы, заканчивающиеся на .plot считаются генерируемыми и удаляются через make clean -->
+# Обработка <> прака
+
+
diff --git a/107/compile_flags.txt b/107/compile_flags.txt
new file mode 100644
index 0000000..34ae930
--- /dev/null
+++ b/107/compile_flags.txt
@@ -0,0 +1,4 @@
+-Iinclude
+-std=c++2c
+-mavx2
+
diff --git a/107/data1 b/107/data1
new file mode 100644
index 0000000..419b8c2
--- /dev/null
+++ b/107/data1
@@ -0,0 +1,5 @@
+__name__	b	sb	a1	a2	a3	a	sa	mu	smu
+b1_weigh	0.1	?	0.0315	0.033	0.037	?	?	?	?
+b1		0.1	?	0.032	0.028	0.027	?	?	?	?
+b2_weigh	0.1	?	0.035	0.029	0.03	?	?	?	?
+b2		0.1	?	0.036	0.033	0.027	?	?	?	?
diff --git a/107/data21 b/107/data21
new file mode 100644
index 0000000..5198f10
--- /dev/null
+++ b/107/data21
@@ -0,0 +1,5 @@
+__name__	b	sb	a1	a2	a3	a	sa	mu	smu
+b1		0.165	?	0.046	0.048	0.049	?	?	?	?
+b1_weig		0.169	?	0.047	0.046	0.046	?	?	?	?
+b2		0.203	?	0.062	0.063	0.063	?	?	?	?
+b2_weig		0.195	?	0.058	0.059	0.059	?	?	?	?
diff --git a/107/data22 b/107/data22
new file mode 100644
index 0000000..e7614ef
--- /dev/null
+++ b/107/data22
@@ -0,0 +1,5 @@
+__name__	b	sb	a1	a2	a3	a	sa	mu	smu
+b1		0.158	?	0.046	0.048	0.047	?	?	?	?
+b1_weig		0.1	?	0.024	0.029	0.029	?	?	?	?
+b2		0.1	?	0.031	0.033	0.033	?	?	?	?
+b2_weig		0.1	?	0.030	0.029	0.030	?	?	?	?
diff --git a/107/main b/107/main
new file mode 100755
index 0000000..3d5308e
--- /dev/null
+++ b/107/main
diff --git a/107/main.cpp b/107/main.cpp
new file mode 100644
index 0000000..e731a06
--- /dev/null
+++ b/107/main.cpp
@@ -0,0 +1,46 @@
+#include "include/praktable.hpp"
+#include <functional>
+
+using table = prak::table<double>;
+
+double mu(const std::vector<double> &ab) {
+	return ab[0] / ab[1];
+}
+
+void proc_table(table &t) {
+	using namespace std::placeholders;
+
+	t.fill_column("sb", 0.003); // 3 millimeters
+	t.apply(prak::avg<double>, {"a1", "a2", "a3"}, "a");
+	t.apply([](const std::vector<double>& args) -> double {
+			return std::sqrt(std::pow(prak::stddev<double>(args), 2) + 0.003*0.003);
+		}, {"a1", "a2", "a3"}, "sa"); // error = sqrt(stddev^2 + systerr^2)
+	t.apply(mu, {"a", "b"}, "mu");
+	t.apply([](const std::vector<double> &arg) -> double {
+			std::vector<double> args = {arg[0], arg[1]};
+			std::vector<double> sargs = {arg[2], arg[3]};
+			return prak::sigma<double>(mu, args, sargs);
+		}, {"a", "b", "sa", "sb"}, "smu");
+}
+
+void ex1(void) {
+	table t;
+	t.read("data1");
+	proc_table(t);
+	std::cout << "Таблица для 1 упражнения: " << t;
+}
+void ex2(void) {
+	table a1, a2;
+	a1.read("data21");
+	a2.read("data22");
+	proc_table(a1);
+	proc_table(a2);
+	std::cout << "Таблица для 2.1: " << a1;
+	std::cout << "Таблица для 2.2: " << a2;
+}
+
+int main() {
+	ex1();
+	ex2();
+	return 0;
+}
diff --git a/107/plots.gp b/107/plots.gp
new file mode 100644
index 0000000..702408a
--- /dev/null
+++ b/107/plots.gp
@@ -0,0 +1,14 @@
+set term pngcairo size 1000, 800
+set tmargin at screen 0.95
+
+f1(x) = a1*x+b1
+fit f1(x) '.plot' using 1:2:3 yerr via a1, b1
+
+set output ''
+set label "" at graph 0.5, graph 1.025 center
+set xlabel ""
+set ylabel ""
+
+plot 	'.plot' using 1:2:3 with yerrorbars notitle lc 0 pt 1 lw 2,	\
+	f1(x) title "" lc rgb "red",				\
+
diff --git a/compile_flags.txt b/compile_flags.txt
new file mode 100644
index 0000000..34ae930
--- /dev/null
+++ b/compile_flags.txt
@@ -0,0 +1,4 @@
+-Iinclude
+-std=c++2c
+-mavx2
+
diff --git a/libprakpp/include/prakcommon.hpp b/libprakpp/include/prakcommon.hpp
index 8d1b001..c58040e 100644
--- a/libprakpp/include/prakcommon.hpp
+++ b/libprakpp/include/prakcommon.hpp
@@ -5,6 +5,25 @@
 #include <vector>
 #include <iostream>
 
+typedef void		i0;
+typedef int8_t		i8;
+typedef uint8_t		u8;
+typedef int16_t		i16;
+typedef uint16_t	u16;
+typedef int32_t		i32;
+typedef uint32_t	u32;
+typedef int64_t		i64;
+typedef uint64_t	u64;
+typedef ssize_t		isz;
+typedef size_t		usz;
+typedef float		f32;
+typedef double		f64;
+#if __SIZEOF_LONG_DOUBLE__ == 16
+typedef long double	f128;
+#else
+typedef long double	_f64;
+#endif
+
 #if defined(_MSC_VER) || !defined(__cpp_multidimensional_subscript) || __cplusplus < 202110L
 #warning "can not use multidimentional subscript operator: falling back to `operator()`"
 #undef MDSUBSCRIPT
diff --git a/libprakpp/include/prakmath.hpp b/libprakpp/include/prakmath.hpp
index 3a4e4db..a5eb0b8 100644
--- a/libprakpp/include/prakmath.hpp
+++ b/libprakpp/include/prakmath.hpp
@@ -2,6 +2,7 @@
 
 #include <cmath>
 #include <concepts>
+#include <numeric>
 
 #ifdef __x86_64__
 #include <immintrin.h>
@@ -184,6 +185,25 @@ scalar:
 	return linear + finalize(buf);
 }
 
+template <arithmetic T>
+T avg(const std::vector<T> &args) {
+	T init{};
+	for (const T &x : args) {
+		init += x;
+	}
+	return init / args.size();
+}
+
+template <arithmetic T>
+T stddev(const std::vector<T> &args) {
+	T sum = {};
+	const T a = avg<T>(args);
+	for (T el : args) {
+		sum += (a-el)*(a-el);
+	}
+	return std::sqrt(sum/args.size()/(args.size()-1));
+}
+
 // take a derivative of function `f` with arguments `at` and with differentiable variable being at index `varidx`
 template <std::floating_point T>
 T deriv4(function_t<T> f, std::vector<T> /*I actually do want a copy here*/ at, size_t varidx) {
@@ -204,7 +224,7 @@ T deriv4(function_t<T> f, std::vector<T> /*I actually do want a copy here*/ at,
 
 /// get error of the calculated value 
 template <std::floating_point T>
-T sigma(function_t<T> f, const std::vector<T> &args, const std::vector<T> sigmas) noexcept(false) {
+T sigma(function_t<T> f, const std::vector<T> &args, const std::vector<T> &sigmas) noexcept(false) {
 	if (args.size() != sigmas.size()) throw dimension_error("function prak::sigma : Args.size() does not match sigmas.size()");
 	T sum = 0;
 	for (size_t i = 0; i < args.size(); ++i) {
@@ -277,7 +297,7 @@ void least_squares_linear(
 /// May throw std::bad_optional_access
 template <typename T>
 std::enable_if<std::is_arithmetic_v<T>, std::vector<pvalue<T>>> 
-polynomial_regression(
+polynominal_regression(
 		size_t degree, 
 		std::vector<T> data_x, 
 		std::vector<T> data_y, 
diff --git a/libprakpp/include/prakmatrix.hpp b/libprakpp/include/prakmatrix.hpp
index 87b38b4..53d3b4b 100644
--- a/libprakpp/include/prakmatrix.hpp
+++ b/libprakpp/include/prakmatrix.hpp
@@ -3,8 +3,8 @@
 #include "prakcommon.hpp"
 
 #include <cstring>
-#include <iomanip>
 #include <ostream>
+#include <optional>
 #include <vector>
 
 namespace prak {
diff --git a/libprakpp/include/praktable.hpp b/libprakpp/include/praktable.hpp
index f32d00d..70f6d49 100644
--- a/libprakpp/include/praktable.hpp
+++ b/libprakpp/include/praktable.hpp
@@ -1,5 +1,6 @@
 #pragma once
 
+#include <cassert>
 #include <cstddef>
 #include <functional>
 #include <algorithm>
@@ -96,7 +97,7 @@ public:
 		iterator operator++(int) { iterator ret = *this; ++(*this); return ret; }
 		bool operator==(iterator other) { return data_index == other.data_index && parent == other.parent && col_index == other.col_index; }
 		bool operator!=(iterator other) { return data_index != other.data_index || parent != other.parent || col_index != other.col_index; }
-		value_type operator*() { return parent->data[data_index]; };
+		value_type &operator*() { return parent->data[data_index]; };
 	};
 	/// Optional rownames: names of rows
 	std::vector<std::string> opt_rownames;
@@ -108,16 +109,23 @@ public:
 	/// default constructor
 	table() = default;
 
+	explicit table(const std::vector<std::string> &columns, size_t rows, const dtype &deflt) 
+		: rows{rows}, columns{columns.size()} 
+	{
+		names = columns;
+		data = std::vector<dtype>(rows * columns.size(), deflt);
+	}
+
 	/// Data: array of ararys, not freed automatically.
-	explicit table(const std::vector<std::string> &strings, dtype **data, size_t rows /*size_t columns = strings.size()*/)
-		: rows{rows}, columns{strings.size()} 
+	explicit table(const std::vector<std::string> &columns, dtype **data, size_t rows /*size_t columns = strings.size()*/)
+		: rows{rows}, columns{columns.size()} 
 	{
-		names = strings;
+		names = columns;
 
-		data = std::vector<dtype>(rows * strings.size());
+		data = std::vector<dtype>(rows * columns.size());
 		for (size_t i = 0; i < rows; ++i)
-			for (size_t j = 0; j < strings.size(); ++j)
-				data[i * strings.size() + j] = data[i][j];
+			for (size_t j = 0; j < columns.size(); ++j)
+				data[i * columns.size() + j] = data[i][j];
 	}
 	
 	/// Strings: names for columns
@@ -137,10 +145,16 @@ public:
 		}
 	}
 
+	explicit table(const std::string &file) {
+		read(file);
+	}
+
 	iterator begin(std::string column) { return iterator(this, column); }
 	iterator end(std::string column) { return iterator(this, column, rows); }
 
-	dtype & SUBSCR_OPRTR (const std::string &column, size_t row) {
+	dtype & SUBSCR_OPRTR (const std::string &column, size_t row) noexcept(false) {
+		size_t i = index(column);
+		if (i == columns) throw std::out_of_range("Column " + column + " does not exist");
 		return data.at(names.size() * row + index(column));
 	}
 
@@ -196,12 +210,14 @@ public:
 				v[j] = SUBSCR_OPRTR(args[j], i);
 			if (result.has_value()) data[columns * i + result_index] = function(v);
 			else (void)function(v);
-		}	
+		}
+		/* print(std::cerr); */
 		return *this;
 	}
 	
 	/// adds a column with name `name` and data `column_data`
 	void add_column(std::string name, std::vector<dtype> column_data) {
+		if (column_data.size() == 0) column_data = std::vector<dtype>(rows, dtype{});
 		std::vector<dtype> data_new(rows * (++columns));
 
 		for (size_t row = 0; row < rows; ++row) {
@@ -215,6 +231,7 @@ public:
 
 	/// Appends a column to the table. if name is set, appends it to `opt_rownames`
 	void add_row(std::vector<dtype> values, std::optional<std::string> name = std::nullopt) {
+		if (values.size() == 0) values = std::vector<dtype>(columns, dtype{});
 		data.resize(columns * (++rows));
 		std::copy_n(values.cbegin(), columns, data.end() - columns);
 		if (name.has_value()) opt_rownames.push_back(*name);
@@ -224,7 +241,7 @@ public:
 		t.print(os);
 		return os;
 	}
-	
+
 	/// Reads a table from a file in a format:
 	/// ```
 	/// col1 col2 col3 ...
@@ -251,7 +268,9 @@ public:
 			names.push_back(buffer);
 		
 		std::vector<dtype> tmp_row(names.size());
+		int __i = 0;
 		while (!(f >> std::ws).eof()) {
+			++__i;
 			if (read_names) { 
 				f >> buffer;
 				opt_rownames.push_back(buffer);
@@ -269,9 +288,25 @@ public:
 		}
 		columns = names.size();
 	}
+	
+	/// Reads a table from a file specified by `path`. 
+	/// For details, refer to documentation of `void read(std::ifstream&)` overload
+	void read(const std::string &path) {
+		std::ifstream f(path);
+		read(f);
+	}
+
+	/// Fills a specified column with the same value `v`
+	void fill_column(const std::string &column, dtype v) {
+		apply([&v](const std::vector<dtype>& _) -> dtype { return v; }, {}, column);
+	}
 
 	/// returns an std::pair with coefficients A and B in that order
-	std::pair<prak::pvalue<dtype>, prak::pvalue<dtype>> least_squares_linear(std::string x, std::string y, std::optional<std::string> sigma = std::nullopt) {
+	std::pair<prak::pvalue<dtype>, prak::pvalue<dtype>> 
+	least_squares_linear(std::string x, std::string y, std::optional<std::string> sigma, std::optional<dtype> sigma_fixed) 
+	noexcept(false) {
+		if (sigma.has_value() == sigma_fixed.has_value()) 
+			throw std::invalid_argument("sigma and sigma_fixed can't both have (no) value");
 		prak::vector<dtype> _x(rows);
 		prak::vector<dtype> _y(rows);
 		prak::vector<dtype> _s(rows);
@@ -279,13 +314,26 @@ public:
 		std::copy(begin(x), end(x), _x.begin());
 		std::copy(begin(y), end(y), _y.begin());
 		if (sigma.has_value()) std::copy(begin(*sigma), end(*sigma), _s.begin());
-		else _s = prak::vector<dtype>(rows, static_cast<dtype>(1));
+		else _s = prak::vector<dtype>(rows, static_cast<dtype>(*sigma_fixed));
 
 		std::pair<prak::pvalue<dtype>, prak::pvalue<dtype>> ret;
 		prak::least_squares_linear<dtype>(_x, _y, _s, ret.first, ret.second);
 		return ret;
 	}
 
+	/// calculate an average of the column 
+	dtype col_avg(const std::string &column) {
+		dtype accum = dtype{};
+		for (auto it = begin(column); it != end(column); ++it) 
+			accum += *it;
+		return accum / rows;
+	}
+
+	/// calculate standard deviation of the column
+	dtype col_stddev(const std::string &column) {
+		assert(0);
+	}
+
 	/// Serialize data in format `data[args[0]][i] data[args[1]][i] data[args[2]][i]...`
 	void print_plot(const stringvec &args, std::ostream &out = std::cout) const {
 		std::vector<size_t> offsets(args.size());
@@ -307,11 +355,17 @@ public:
 		if (yss.has_value()) ssi = index(*yss);
 		for (size_t row = 0; row < rows; ++row) {
 			size_t offset = columns * row;
-			out << data[offset + xsi] << ' ' << data[offset + ysi];
+			out << data.at(offset + xsi) << ' ' << data.at(offset + ysi);
 			if (ssi != nosigma) out << ' ' << data[offset+ssi];
 			out << std::endl;
 		}
 	}
+
+	/// Serialize data into a file `file`. For details, refer to documentation for overload with std::ifstream as an argument
+	void write_plot(const std::string &file, const std::string &xs, const std::string &ys, std::optional<std::string> yss = std::nullopt) const {
+		std::ofstream out(file);
+		write_plot(xs, ys, yss, out);
+	}
 	
 	void plot_png(
 		const std::string output_filename, 
diff --git a/vtek3/main b/vtek3/main
deleted file mode 100755
index 08e6ab8..0000000
--- a/vtek3/main
+++ /dev/null