diff --git a/src/components/chart/LimitBuilder.vue b/src/components/chart/LimitBuilder.vue
index 8a8820b..c32bc6d 100644
--- a/src/components/chart/LimitBuilder.vue
+++ b/src/components/chart/LimitBuilder.vue
@@ -55,7 +55,6 @@ import {HLine} from "@/charts/shape.js";
 const s = useStore()
 const os = useOrderStore()
 const co = useChartOrderStore()
-const theme = useTheme().current
 const props = defineProps(['order', 'builder'])
 const emit = defineEmits(['update:builder'])
 
@@ -251,6 +250,7 @@ function setModelValue(model, value) {
 
 <style scoped lang="scss">
 td.weight {
+  width: 11em;
   padding-left: 0.5em;
   padding-right: 0.5em;
   text-align: right;
diff --git a/src/components/chart/RungBuilder.vue b/src/components/chart/RungBuilder.vue
index cd871b1..e9616b7 100644
--- a/src/components/chart/RungBuilder.vue
+++ b/src/components/chart/RungBuilder.vue
@@ -41,6 +41,7 @@ import {linspace, sideColor} from "@/misc.js";
 import {computed, watchEffect} from "vue";
 import Color from "color";
 import {cancelDrawing} from "@/charts/chart.js";
+import {devectorize, vectorAdd, vectorDiv, vectorMul, vectorSub, vectorIsNull, vectorize} from "@/vector.js";
 
 const os = useOrderStore()
 const co = useChartOrderStore()
@@ -55,11 +56,11 @@ const props = defineProps({
   mode: { type: Number, default: 0 }, // rung addition mode: 0 = split, 1 = extend
   flip: { type: Boolean, default: false }, // if true, the skew slider is flipped upside-down
   orientation: { type: Number, default: 1 },  // 0 = horizontal slider, 1 = vertical
+  // values may be scalars or vector arrays
   getModelValue: Function,  // getModelValue(model) -> value
   setModelValue: Function,  // setModelValue(model,value) -> void
-  getPointsValue: Function,  // getValueFromPoints(points) -> value
   setValues: Function,  // setValues(values:Array) -> void
-  setWeights: Function,  // setValues(values:Array) -> void
+  setWeights: Function,  // setWeights(values:Array) -> void
 })
 
 const flippedSign = computed(()=>props.flip?-1:1)
@@ -88,37 +89,38 @@ const rungs = computed({
       return
     }
     let [a,b] = endpoints.value
-    const prevR = props.builder.rungs
     r = Number(r)
+    const prevR = Number(props.builder.rungs)
     props.builder.rungs = r
-    // console.log('set rungs', r, ...endpoints.value)
-    if ( r > 0 && b === null ) {
+    console.log('set rungs', prevR, r, a, b)
+    if ( r > 0 && vectorIsNull(b) ) {
+      console.log('convert to range')
       // convert single shape to a range
       if (props.mode===0) {
         const width = props.stdWidth
         const mid = a
-        a = mid - width/2
-        b = mid + width/2
+        a = vectorAdd(mid, -width/2)
+        b = vectorAdd(mid, +width/2)
         endpoints.value = [a,b]
       }
       else if (props.mode===1 ) {
-        endpoints.value = [a, a+props.stdWidth]
+        endpoints.value = [a, vectorAdd(a,props.stdWidth)]
       }
       else
         throw Error(`Unknown rung mode ${props.mode}`)
     }
-    else if ( r === 1 && b !== null ) {
+    else if ( r === 1 && !vectorIsNull(b) ) {
       // convert from a range to a single shape
       if (props.mode===0)
-        a = (a + b) / 2
+        a = vectorDiv(vectorAdd(a,b), 2)
       b = null
       endpoints.value = [a, b]
     }
     else {
       // from multi to multi
       if (props.mode===1) {
-        const width = (b - a) / (prevR-1)
-        b = a + width * (r-1)
+        const width = vectorDiv(vectorSub(b, a), (prevR-1))
+        b = vectorMul(vectorAdd(a, width), (r-1))
         endpoints.value = [a, b]
       }
     }
@@ -128,14 +130,27 @@ const rungs = computed({
 
 const values = computed(()=>{
   const [a, b] = endpoints.value
+  console.log('values', a, b)
   const r = props.builder.rungs
   let result
-  if ( a===null || !r )
+  if ( !r || vectorIsNull(a) )
     result = []  // no data
   else if (r===1)
     result = [a]  // single shape
-  else
-    result = linspace(a, b, r)  // linear spacing
+  else {
+    const columns = []
+    for (let i=0; i<a.length; i++)
+      columns.push(linspace(a[i], b[i], r))  // linear spacing for each dimension
+    // transpose
+    result = []
+    for (let i=0; i<r; i++) {
+      const vector = []
+      for (let j=0; j<a.length; j++)
+        vector.push(columns[j][i])
+      result.push(devectorize(vector))
+    }
+  }
+  console.log('vectorized values', result)
   props.setValues(result)
   return result;
 })
@@ -180,11 +195,21 @@ const colorStyle = computed(() => {
 // we keep two special control shapes as the edges of the range, with deletable shapes in-between
 
 function createShape(value, model, onModel, onDelete) {
-  props.setModelValue(model, value)
+  setModelValue(model, value)
   return new props.shape(model, onModel, onDelete)  // props.shape is the constructor function
 }
 
 
+function getModelValue(model) {
+  return vectorize(props.getModelValue(model));
+}
+
+
+function setModelValue(model, value) {
+  props.setModelValue(model, devectorize(value))
+}
+
+
 function translateOnModel(shape) {
   const oldOnModel = shape.onModel
   shape.onModel = function (model, oldModel) {
@@ -192,15 +217,15 @@ function translateOnModel(shape) {
     // console.log('translateOnDrag', this.beingDragged(), shape.ourPoints)
     if (!this.beingDragged())
       return
-    const prev = props.getModelValue(oldModel)
-    const cur = props.getModelValue(this.model)
+    const prev = getModelValue(oldModel)
+    const cur = getModelValue(this.model)
     const delta = cur - prev
     // console.log('delta', shape.id, prev, cur, delta)
     let [a, b] = endpoints.value
     if (delta !== 0) {
-      a += delta
+      a = vectorAdd(a, delta)
       if (rungs.value > 1)
-        b += delta
+        b = vectorAdd(b, delta)
       endpoints.value = [a, b]
     }
   }
@@ -213,7 +238,7 @@ function setModelColor(model) {
 
 const shapeA = createShape(endpoints.value[0], {color: defaultColor},
     function (model) {
-      const value = props.getModelValue(model);
+      const value = getModelValue(model);
       if (value !== endpoints.value[0])
         endpoints.value = [value, endpoints.value[1]]
       setModelColor(model)
@@ -225,7 +250,7 @@ if (props.mode===1)
 
 const shapeB = createShape(endpoints.value[1], {color:defaultColor},
     function (model) {
-      const value = props.getModelValue(model);
+      const value = getModelValue(model);
       if (value !== endpoints.value[1])
         endpoints.value = [endpoints.value[0], value]
       setModelColor(model)
@@ -261,7 +286,7 @@ function makeModel(index) {
     amount: props.order.amount * alloc,
     amountSymbol: amountSymbol.value,
   }
-  props.setModelValue(result, values.value[index])
+  setModelValue(result, values.value[index])
   return result
 }
 
diff --git a/src/vector.js b/src/vector.js
new file mode 100644
index 0000000..6205689
--- /dev/null
+++ b/src/vector.js
@@ -0,0 +1,58 @@
+export function vectorize(value) {
+    if (value === undefined) {
+        console.warn('vectorizing undefined as null')
+        return null
+    }
+    if (value === null)
+        return null
+    if (value.length === undefined)
+        value = [value]
+    return value;
+}
+
+export function devectorize(value) {
+  return value === null || value.length === 0 ? null : value.length === 1 ? value[0] : value
+}
+
+
+export function vectorIsNull(value) {
+    console.log('vectorIsNull', value, value === null || value.length === 1 && value[0] === null)
+  return value === null || value.length === 1 && value[0] === null
+}
+
+
+export function vectorAdd(a, b) {
+  const result = []
+  const scalarB = b.length === undefined
+  for( let i=0; i<a.length; i++ )
+    result.push(a[i]+(scalarB ? b : b[i]))
+  console.log('vectorAdd', a, b, result)
+  return result
+}
+
+export function vectorSub(a, b) {
+  const result = []
+  const scalarB = b.length === undefined
+  for( let i=0; i<a.length; i++ )
+    result.push(a[i]-(scalarB ? b : b[i]))
+  console.log('vectorSub', a, b, result)
+  return result
+}
+
+export function vectorMul(a, b) {
+  const result = []
+  const scalarB = b.length === undefined
+  for( let i=0; i<a.length; i++ )
+    result.push(a[i]*(scalarB ? b : b[i]))
+  console.log('vectorMul', a, b, result)
+  return result
+}
+
+export function vectorDiv(a, b) {
+  const result = []
+  const scalarB = b.length === undefined
+  for( let i=0; i<a.length; i++ )
+    result.push(a[i]/(scalarB ? b : b[i]))
+  console.log('vectorDiv', a, b, result)
+  return result
+}