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# generate::C

Generate C formatted string

### Use only in the MuPAD Notebook Interface.

This functionality does not run in MATLAB.

## Syntax

```generate::C(e, <NoWarning>)
```

## Description

generate::C(e) generates C code for the MuPAD® expression e.

generate::C returns a C formatted string representing an expression, equation, list of equations or a matrix.

An equation represents an assignment in C code. The type of the assignment is double.

When generating C code for a matrix, the generator assigns only nonzero elements. See Example 3.

To print an output string to a file, use the fprint function. Use the printing option Unquoted to remove quotation marks and to expand special characters like line breaks and tabs.

Use the generate::optimize function to optimize the MuPAD code before converting it to C code. See Example 5.

The NoWarning option lets you suppress warnings. See Example 6.

## Examples

### Example 1

The code generator converts a list of equations to a sequence of assignments:

```generate::C([x1 = y2^2*(y1 + sin(z)), x2 = tan(x1^4)]):
print(Unquoted, %)```
```  x1 = (y2*y2)*(y1+sin(z));
x2 = tan(x1*x1*x1*x1);
```

### Example 2

MuPAD matrix and array indexing differs from C array indexing. By default, MuPAD array indices start with 1, and C array indices start with 0. To create the code compatible with the default indexing in C, the generate::C function decrements each index by one:

```A:= matrix([[1,2],[3,4]]):
generate::C(A)."\n".
generate::C(hold(Determinante = A[1,1]*A[2,2] - A[1,2]*A[2,1])):
print(Unquoted, %)```
```  A[0][0] = 1.0;
A[0][1] = 2.0;
A[1][0] = 3.0;
A[1][1] = 4.0;

Determinante = A[0][0]*A[1][1]-A[0][1]*A[1][0];
```

### Example 3

Generated C code does not include assignments for zero elements of a matrix:

```A:= matrix([[1, 0, 0],[0, 0, 1]]):
print(Unquoted, generate::C(A))```
```  A[0][0] = 1.0;
A[1][2] = 1.0;
```

### Example 4

If the first index of an array is not 1, the generate::C function issues a warning:

```A:= array(1..2, 2..3, [[1,2],[3,4]]):
print(Unquoted, generate::C(A))```
```Warning: The array index 'A[1..2, 2..3]' is out of range 1..n. [DOM_ARRAY::CF]
```
```  A[0][1] = 1.0;
A[0][2] = 2.0;
A[1][1] = 3.0;
A[1][2] = 4.0;
```

### Example 5

The generate::C function does not optimize your code:

```print(Unquoted,
generate::C([x = a + b, y = (a + b)^2])):```
```  x = a+b;
y = pow(a+b,2.0);
```

You can use the generate::optimize function before converting your MuPAD expression to C code. For example, this function can reduce the number of operations by finding common subexpressions:

```print(Unquoted,
generate::C(
generate::optimize([x = a + b, y = (a + b)^2])
)):```
```  x = a+b;
y = x*x;
```

### Example 6

By default, the generate::C function can issue warnings:

`print(Unquoted, generate::C(f(x)))`
```Warning: Function "f" is not verified to be a valid C function.
```
```  t0 = f(x);
```

If you started using generate::C recently, the warnings can help you identify the potential issues in the converted code. If you want to suppress warnings, use the NoWarning option:

`print(Unquoted, generate::C(f(x), NoWarning))`
```  t0 = f(x);
```

## Parameters

 e An expression, equation, list of equations, or a matrix

## Options

 NoWarning Suppress warnings.

## Return Values

generate::C returns a string containing C code.

## See Also

### MuPAD Functions

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