diff --git a/m-files/plotdt.m b/m-files/plotdt.m
new file mode 100644
index 0000000..8ff04c2
--- /dev/null
+++ b/m-files/plotdt.m
@@ -0,0 +1,14 @@
+function plotdt(T, idxsch)
+    idxsch *= 2;
+    difrns = T(:,idxsch-1)-T(:,idxsch);
+    D = median(difrns);
+    sgn = '+';
+    if(D < 0) sgn = '-'; endif
+    sigma = std(difrns);
+    printf("T_1(%d) = T_0(%d) %c%.4f +- %.4f\n", idxsch, idxsch, sgn, abs(D), sigma);
+    plot(T(:,1), medfilt1(D-difrns, 5));
+    %plot(T(:,1), T(:,idxsch)-T(:,idxsch-1)+D);
+    xlabel("T, ^\\circ{}C");
+    ylabel(sprintf("T_1-T_0%c%.4f", sgn, abs(D)));
+    title(sprintf("Temperature difference for pair %d (\\sigma=%.4f)", idxsch/2, sigma));
+endfunction
diff --git a/m-files/plotpair.m b/m-files/plotpair.m
new file mode 100644
index 0000000..502d8a1
--- /dev/null
+++ b/m-files/plotpair.m
@@ -0,0 +1,14 @@
+function plotpair(T, idxsch1, idxsch2)
+    i1 = 2*idxsch1-1;
+    i2 = 2*idxsch2-1;
+    difrns = T(:,i1)-T(:,i2);
+    D = median(difrns);
+    sigma = std(difrns);
+    sgn = '+';
+    if(D < 0) sgn = '-'; endif
+    printf("T_0(%d) = T_0(%d) %c%.4f +- %.4f\n", idxsch2, idxsch1, sgn, abs(D), sigma);
+    plot(T(:,1), medfilt1(D-difrns, 5));
+    xlabel("T, ^\\circ{}C");
+    ylabel(sprintf("T(%d_0) - T(%d_0) %c %.4f", idxsch2, idxsch1, sgn, abs(D)));
+    title(sprintf("Temperature difference for sensors %d_0 and %d_0 (\\sigma=%.4f)", idxsch2, idxsch1, sigma));
+endfunction
diff --git a/m-files/readtemp.m b/m-files/readtemp.m
new file mode 100644
index 0000000..85d666e
--- /dev/null
+++ b/m-files/readtemp.m
@@ -0,0 +1,49 @@
+function [tm T goodrecs diffs] = readtemp(name)
+% return arrays of unix time & temperatures from file `name`
+% substitute missed values by interpolation
+    T = dlmread(name);
+    nrecs = size(T, 1);
+    nsensors = size(T, 2) - 1;
+    if(nrecs < 2 || nsensors < 2) return; endif
+    tm = T(:, 1);
+    tm -= tm(1);
+    T(:,1) = [];
+    goodrecs = [];
+    % interpolate missing values
+    for N = 1:nsensors
+        term = T(:, N);
+        badidxs = find(term < -275.);
+        bads = size(badidxs, 1);
+        if(bads > nrecs/2)
+            printf("%d: all (or almost all) data records are bad\n", N);
+            continue;
+        elseif(bads) % some records are bad, try to make interpolation
+            printf("%d: %d bad records\n", N, bads);
+            tmx = tm; Tx = term;
+            tmx(badidxs) = [];
+            Tx(badidxs) = [];
+            T(:, N) = interp1(tmx, Tx, tm, "spline");
+        endif
+        goodrecs = [goodrecs N];
+    endfor
+    % remove strings with NANs
+    ii = find(isnan(T));
+    s = size(T, 1);
+    idxs = ii - s*floor((ii-1)/s);
+    T(idxs, :) = [];
+    tm(idxs) = [];
+    diffs = T - median(T,2);
+    % now remove bad records
+    for N = goodrecs
+        term = abs(diffs(:, N));
+        badidxs = find(term > 3.);
+        bads = size(badidxs, 1);
+        if(bads)
+            tmx = tm; Tx = T(:, N);
+            tmx(badidxs) = [];
+            Tx(badidxs) = [];
+            T(:, N) = interp1(tmx, Tx, tm);
+        endif
+    endfor
+    diffs = T - median(T,2);
+endfunction
diff --git a/m-files/testval.m b/m-files/testval.m
new file mode 100644
index 0000000..03f52b5
--- /dev/null
+++ b/m-files/testval.m
@@ -0,0 +1,29 @@
+function v = testval()
+    K = [34100, 22617, 15996, 7338, 5714];
+    printf("RAW\t\tdouble\tint\n");
+    for raw = 8000000:100000:10000000;
+        ii = getint(K, raw);
+        s = sign(ii);
+        ii = abs(ii);
+        f = floor(ii/100);
+        printf("%10d\t%.2f\t%d.%02d\n", raw, getdouble(K, raw), f*s, ii-100*f);
+    endfor
+endfunction
+
+function T = getdouble(K, raw)
+    val = raw/256.;
+    T = K(1)*(-1.5e-2) + 0.1e-5*val*(K(2) + 1e-5*val*(K(3)*(-2) + 1e-5*val*(4*K(4) + 1e-5*val*(-2)*K(5))));
+endfunction
+
+function T = getint(K, raw)
+    val = int64(raw);
+    mul = int64([0, 1, -2, 4, -2]);
+    tmp = int64(0);
+    for j = 5:-1:2
+        tmp /= 100000;
+        tmp += mul(j) * K(j);
+        tmp *= val;
+        tmp /= 256;
+    endfor
+    T = double(tmp*1e-4 + (-1.5)*K(1));
+endfunction