1---
2title: Control Parameters
3layout: ../../layouts/MainLayout.astro
4---
5
6import { MiniRepl } from '../../docs/MiniRepl';
7import { JsDoc } from '../../docs/JsDoc';
8
9# Control Parameters
10
11Besides functions that control time, we saw earlier that functions like `note` and `cutoff` control different parameters (short params) of an event.
12Let's now look more closely at how these `param(eter) functions` work.
13
14# Parameter Functions
15
16A very powerful feature of tidal patterns is that each parameter can be controlled independently:
17
18<MiniRepl
19  client:only="react"
20  tune={`note("c a f e")
21.cutoff("<500 1000 2000 [4000 8000]>")
22.gain(.8)
23.s('sawtooth')
24.log()`}
25/>
26
27In this example, the parameters `note`, `cutoff`, `gain` and `s` are controlled independently by either patterns or plain values (numbers / text).
28After pressing play, we can observe the time and parameter values of each event (hap) in the output created by `.log()`.
29
30## Plain vs Parameterized Values
31
32Patterns that are not wrapped inside a param function will contain unlabeled `plain values`:
33
34<MiniRepl client:only="react" tune={`"<c e g>".log()`} />
35
36This will not generate any sound output, because Strudel could only guess which param is meant by these letters.
37
38Now compare that to the version wrapped in `note`:
39
40<MiniRepl client:only="react" tune={`note("<c e g>").log()`} />
41
42Now it is clear that these letters are meant to be played as notes.
43Under the hood, the `note` function (as well as all other param functions)
44will wrap each plain value in an object. If the note function did not exist, we would need to write:
45
46<MiniRepl client:only="react" tune={`cat({note:'c'},{note:'e'},{note:'g'}).log()`} />
47
48This will have the same output, though it is rather unwieldy to read and write.
49
50## Wrapping Parameter Functions
51
52To avoid too much nesting, param functions can also be chained like this:
53
54<MiniRepl client:only="react" tune={`cat('c', 'e', 'g').note().log()`} />
55
56This is equivalent to `note(cat('c','e','g')).log()`.
57
58You can use this with any function that declares a type (like `n`, `s`, `note`, `freq` etc), just make sure to leave the parens empty!
59
60## Plain Value Modification
61
62Patterns of plain values can be modified with any of the following operators:
63
64<MiniRepl client:only="react" tune={`"50 60 70".add("<0 1 2>").log()`} />
65
66Here, the add function modifies the numbers on the left.
67Again, there is no output because these numbers have no meaning without a param.
68
69## Param Value Modification
70
71To modify a parameter value, you can either:
72
73- Use the operator on the plain value pattern, inside the param function:
74
75  <MiniRepl client:only="react" tune={`note("50 60 70".add("<0 1 2>")).room(.1).log()`} />
76
77- Similarly, use the operator on the plain value pattern and wrap it later:
78
79  <MiniRepl client:only="react" tune={`"50 60 70".add("<0 1 2>").note().room(.1).log()`} />
80
81- Specify which param should be modified inside the operator function:
82
83  <MiniRepl client:only="react" tune={`note("50 60 70").room(.1).add(note("<0 1 2>")).log()`} />
84
85Remember the execution of the chained functions goes from left to right.
86
87# Operators
88
89This group of functions allows to modify the value of events.
90
91## add
92
93<JsDoc client:idle name="Pattern.add" h={0} />
94
95## sub
96
97<JsDoc client:idle name="Pattern.sub" h={0} />
98
99## mul
100
101<JsDoc client:idle name="Pattern.mul" h={0} />
102
103## div
104
105<JsDoc client:idle name="Pattern.div" h={0} />
106
107## round
108
109<JsDoc client:idle name="Pattern.round" h={0} />
110
111## floor
112
113<JsDoc client:idle name="Pattern.floor" h={0} />
114
115## ceil
116
117<JsDoc client:idle name="Pattern.ceil" h={0} />
118
119## range
120
121<JsDoc client:idle name="Pattern.range" h={0} />
122
123## rangex
124
125<JsDoc client:idle name="Pattern.rangex" h={0} />
126
127## range2
128
129<JsDoc client:idle name="Pattern.range2" h={0} />
130
131## ratio
132
133<JsDoc client:idle name="Pattern.ratio" h={0} />
134
135## as
136
137<JsDoc client:idle name="as" h={0} />
138
139# Custom Parameters
140
141You can also create your own parameters:
142
143<MiniRepl
144  client:only="react"
145  tune={`let x = createParam('x')
146x(sine.range(0, 200))
147`}
148/>
149
150Multiple params can also be created in a more consice way, using `createParams`:
151
152<MiniRepl
153  client:only="react"
154  tune={`let { x, y } = createParams('x', 'y');
155x(sine.range(0, 200)).y(cosine.range(0, 200));
156`}
157/>
158
159Note that these params will not do anything until you give them meaning in your custom output!
160
161From modifying parameters we transition to the concept of [Signals](/learn/signals).